Adding a ShareView and ActionProvider for menus.

1. Adding a widget for sharing contenet with other applications.
   The widget orders the share targets based on previous shares.
   It displays the share target list as either a popup anchored to
   itslef or as a dialog.

2. Added a ShareDataModel that will back widgets or other classes
   that are interested in share targets for a given intent ordered
   according to share history. This class is backing the ShareView

3. Added ActionProvider mechanism for the MenuItems. The action
   provider of a menu creates the action view as well as performs
   a default action if the menu item is on the overflow menu and
   is triggered but none of the menu callback has handled that.

bug:4590827

Change-Id: Iaa4add2df2538b8c6c7edbeaf2880486d4fd75c5

15 files changed, 2488 insertions, 26 deletions

diff --git a/core/java/android/view/ActionProvider.java b/core/java/android/view/ActionProvider.java
new file mode 100644
index 0000000..6491da0
--- /dev/null
+++ b/core/java/android/view/ActionProvider.java
@@ -0,0 +1,114 @@
+/*
+ * Copyright (C) 2011 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package android.view;
+
+import android.content.Context;
+
+/**
+ * This class is a mediator for accomplishing a given task, for example sharing a file.
+ * It is responsible for creating a view that performs an action that accomplishes the task.
+ * This class also implements other functions such a performing a default action.
+ * <p>
+ * An ActionProvider can be optionally specified for a {@link MenuItem} and in such a
+ * case it will be responsible for creating the action view that appears in the
+ * {@link android.app.ActionBar} as a substitute for the menu item when the item is
+ * displayed as an action item. Also the provider is responsible for performing a
+ * default action if a menu item placed on the overflow menu of the ActionBar is
+ * selected and none of the menu item callbacks has handled the selection.
+ * </p>
+ * <p>
+ * There are two ways for using an action provider for creating and handling of action views:
+ * <ul>
+ * <li>
+ * Setting the action provider on a {@link MenuItem} directly by calling
+ * {@link MenuItem#setActionProvider(ActionProvider)}.
+ * </li>
+ * <li>
+ * Declaring the action provider in the menu XML resource. For example:
+ * <pre>
+ * <code>
+ *   &lt;item android:id="@+id/my_menu_item"
+ *     android:title="Title"
+ *     android:icon="@drawable/my_menu_item_icon"
+ *     android:showAsAction="ifRoom"
+ *     android:actionProviderClass="foo.bar.SomeActionProvider" /&gt;
+ * </code>
+ * </pre>
+ * </li>
+ * </ul>
+ * </p>
+ *
+ * @see MenuItem#setActionProvider(ActionProvider)
+ * @see MenuItem#getActionProvider()
+ */
+public abstract class ActionProvider {
+
+    /**
+     * Creates a new instance.
+     *
+     * @param context Context for accessing resources.
+     */
+    public ActionProvider(Context context) {
+    }
+
+    /**
+     * Factory method for creating new action views.
+     *
+     * @return A new action view.
+     */
+    public abstract View onCreateActionView();
+
+    /**
+     * Performs an optional default action.
+     * <p>
+     * For the case of an action provider placed in a menu item not shown as an action this
+     * method is invoked if none of the callbacks for processing menu selection has handled
+     * the event.
+     * </p>
+     * <p>
+     * A menu item selection is processed in the following order:
+     * <ul>
+     * <li>
+     * Receiving a call to {@link MenuItem.OnMenuItemClickListener#onMenuItemClick
+     *  MenuItem.OnMenuItemClickListener.onMenuItemClick}.
+     * </li>
+     * <li>
+     * Receiving a call to {@link android.app.Activity#onOptionsItemSelected(MenuItem)
+     *  Activity.onOptionsItemSelected(MenuItem)}
+     * </li>
+     * <li>
+     * Receiving a call to {@link android.app.Fragment#onOptionsItemSelected(MenuItem)
+     *  Fragment.onOptionsItemSelected(MenuItem)}
+     * </li>
+     * <li>
+     * Launching the {@link android.content.Intent} set via
+     * {@link MenuItem#setIntent(android.content.Intent) MenuItem.setIntent(android.content.Intent)}
+     * </li>
+     * <li>
+     * Invoking this method.
+     * </li>
+     * </ul>
+     * </p>
+     * <p>
+     * The default implementation does not perform any action.
+     * </p>
+     *
+     * @param actionView A view created by {@link #onCreateActionView()}.
+     */
+    public void onPerformDefaultAction(View actionView) {
+    }
+}
diff --git a/core/java/android/view/MenuInflater.java b/core/java/android/view/MenuInflater.java
index 372ac15..a7f0cba 100644
--- a/core/java/android/view/MenuInflater.java
+++ b/core/java/android/view/MenuInflater.java
@@ -26,6 +26,7 @@ import android.content.Context;
 import android.content.res.TypedArray;
 import android.content.res.XmlResourceParser;
 import android.util.AttributeSet;
+import android.util.Log;
 import android.util.Xml;
 
 import java.io.IOException;
@@ -42,6 +43,8 @@ import java.lang.reflect.Method;
  * <em>something</em> file.)
  */
 public class MenuInflater {
+    private static final String LOG_TAG = "MenuInflater";
+
     /** Menu tag name in XML. */
     private static final String XML_MENU = "menu";
     
@@ -53,10 +56,16 @@ public class MenuInflater {
 
     private static final int NO_ID = 0;
     
-    private static final Class<?>[] ACTION_VIEW_CONSTRUCTOR_SIGNATURE = new Class[]{Context.class};
+    private static final Class<?>[] ACTION_VIEW_CONSTRUCTOR_SIGNATURE = new Class[] {Context.class};
+
+    private static final Class<?>[] ACTION_PROVIDER_CONSTRUCTOR_SIGNATURE = ACTION_VIEW_CONSTRUCTOR_SIGNATURE;
+
+    private final Object[] mActionViewConstructorArguments;
+
+    private final Object[] mActionProviderConstructorArguments;
 
     private Context mContext;
-    
+
     /**
      * Constructs a menu inflater.
      * 
@@ -64,6 +73,8 @@ public class MenuInflater {
      */
     public MenuInflater(Context context) {
         mContext = context;
+        mActionViewConstructorArguments = new Object[] {context};
+        mActionProviderConstructorArguments = mActionViewConstructorArguments;
     }
 
     /**
@@ -172,14 +183,14 @@ public class MenuInflater {
     
     private static class InflatedOnMenuItemClickListener
             implements MenuItem.OnMenuItemClickListener {
-        private static final Class[] PARAM_TYPES = new Class[] { MenuItem.class };
+        private static final Class<?>[] PARAM_TYPES = new Class[] { MenuItem.class };
         
         private Context mContext;
         private Method mMethod;
         
         public InflatedOnMenuItemClickListener(Context context, String methodName) {
             mContext = context;
-            Class c = context.getClass();
+            Class<?> c = context.getClass();
             try {
                 mMethod = c.getMethod(methodName, PARAM_TYPES);
             } catch (Exception e) {
@@ -255,7 +266,8 @@ public class MenuInflater {
 
         private int itemActionViewLayout;
         private String itemActionViewClassName;
-        
+        private String itemActionProviderClassName;
+
         private String itemListenerMethodName;
         
         private static final int defaultGroupId = NO_ID;
@@ -333,9 +345,10 @@ public class MenuInflater {
             itemListenerMethodName = a.getString(com.android.internal.R.styleable.MenuItem_onClick);
             itemActionViewLayout = a.getResourceId(com.android.internal.R.styleable.MenuItem_actionLayout, 0);
             itemActionViewClassName = a.getString(com.android.internal.R.styleable.MenuItem_actionViewClass);
-            
+            itemActionProviderClassName = a.getString(com.android.internal.R.styleable.MenuItem_actionProviderClass);
+
             a.recycle();
-            
+
             itemAdded = false;
         }
 
@@ -377,20 +390,35 @@ public class MenuInflater {
                 }
             }
 
+            boolean actionViewSpecified = false;
             if (itemActionViewClassName != null) {
-                try {
-                    final Class<?> clazz = Class.forName(itemActionViewClassName, true,
-                            mContext.getClassLoader());
-                    Constructor<?> c = clazz.getConstructor(ACTION_VIEW_CONSTRUCTOR_SIGNATURE);
-                    item.setActionView((View) c.newInstance(mContext));
-                } catch (Exception e) {
-                    throw new InflateException(e);
+                View actionView = (View) newInstance(itemActionViewClassName,
+                        ACTION_VIEW_CONSTRUCTOR_SIGNATURE, mActionViewConstructorArguments);
+                item.setActionView(actionView);
+                actionViewSpecified = true;
+            }
+            if (itemActionViewLayout > 0) {
+                if (!actionViewSpecified) {
+                    item.setActionView(itemActionViewLayout);
+                    actionViewSpecified = true;
+                } else {
+                    Log.w(LOG_TAG, "Ignoring attribute 'itemActionViewLayout'."
+                            + " Action view already specified.");
+                }
+            }
+            if (itemActionProviderClassName != null) {
+                if (!actionViewSpecified) {
+                    ActionProvider actionProvider = newInstance(itemActionProviderClassName,
+                            ACTION_PROVIDER_CONSTRUCTOR_SIGNATURE,
+                            mActionProviderConstructorArguments);
+                    item.setActionProvider(actionProvider);
+                } else {
+                    Log.w(LOG_TAG, "Ignoring attribute 'itemActionProviderClass'."
+                            + " Action view already specified.");
                 }
-            } else if (itemActionViewLayout > 0) {
-                item.setActionView(itemActionViewLayout);
             }
         }
-        
+
         public void addItem() {
             itemAdded = true;
             setItem(menu.add(groupId, itemId, itemCategoryOrder, itemTitle));
@@ -406,6 +434,18 @@ public class MenuInflater {
         public boolean hasAddedItem() {
             return itemAdded;
         }
+
+        @SuppressWarnings("unchecked")
+        private <T> T newInstance(String className, Class<?>[] constructorSignature,
+                Object[] arguments) {
+            try {
+                Class<?> clazz = mContext.getClassLoader().loadClass(className);
+                Constructor<?> constructor = clazz.getConstructor(constructorSignature);
+                return (T) constructor.newInstance(arguments);
+            } catch (Exception e) {
+                Log.w(LOG_TAG, "Cannot instantiate class: " + className, e);
+            }
+            return null;
+        }
     }
-    
 }
diff --git a/core/java/android/view/MenuItem.java b/core/java/android/view/MenuItem.java
index dc68264..ccd8353 100644
--- a/core/java/android/view/MenuItem.java
+++ b/core/java/android/view/MenuItem.java
@@ -88,7 +88,6 @@ public interface MenuItem {
      * @see MenuItem#expandActionView()
      * @see MenuItem#collapseActionView()
      * @see MenuItem#setShowAsActionFlags(int)
-     * @see MenuItem#
      */
     public interface OnActionExpandListener {
         /**
@@ -480,6 +479,10 @@ public interface MenuItem {
      * Set an action view for this menu item. An action view will be displayed in place
      * of an automatically generated menu item element in the UI when this item is shown
      * as an action within a parent.
+     * <p>
+     *   <strong>Note:</strong> Setting an action view overrides the action provider
+     *           set via {@link #setActionProvider(ActionProvider)}.
+     * </p>
      *
      * @param view View to use for presenting this item to the user.
      * @return This Item so additional setters can be called.
@@ -492,6 +495,10 @@ public interface MenuItem {
      * Set an action view for this menu item. An action view will be displayed in place
      * of an automatically generated menu item element in the UI when this item is shown
      * as an action within a parent.
+     * <p>
+     *   <strong>Note:</strong> Setting an action view overrides the action provider
+     *           set via {@link #setActionProvider(ActionProvider)}.
+     * </p>
      *
      * @param resId Layout resource to use for presenting this item to the user.
      * @return This Item so additional setters can be called.
@@ -511,6 +518,32 @@ public interface MenuItem {
     public View getActionView();
 
     /**
+     * Sets the {@link ActionProvider} responsible for creating an action view if
+     * the item is placed on the action bar. The provider also provides a default
+     * action invoked if the item is placed in the overflow menu.
+     * <p>
+     *   <strong>Note:</strong> Setting an action provider overrides the action view
+     *           set via {@link #setActionView(int)} or {@link #setActionView(View)}.
+     * </p>
+     *
+     * @param actionProvider The action provider.
+     * @return This Item so additional setters can be called.
+     *
+     * @see ActionProvider
+     */
+    public MenuItem setActionProvider(ActionProvider actionProvider);
+
+    /**
+     * Gets the {@link ActionProvider}.
+     *
+     * @return The action provider.
+     *
+     * @see ActionProvider
+     * @see #setActionProvider(ActionProvider)
+     */
+    public ActionProvider getActionProvider();
+
+    /**
      * Expand the action view associated with this menu item.
      * The menu item must have an action view set, as well as
      * the showAsAction flag {@link #SHOW_AS_ACTION_COLLAPSE_ACTION_VIEW}.
diff --git a/core/java/android/widget/ActivityChooserModel.java b/core/java/android/widget/ActivityChooserModel.java
new file mode 100644
index 0000000..83f80ff
--- /dev/null
+++ b/core/java/android/widget/ActivityChooserModel.java
@@ -0,0 +1,1115 @@
+/*
+ * Copyright (C) 2011 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package android.widget;
+
+import android.content.ComponentName;
+import android.content.Context;
+import android.content.Intent;
+import android.content.pm.ResolveInfo;
+import android.database.DataSetObservable;
+import android.database.DataSetObserver;
+import android.os.AsyncTask;
+import android.os.Handler;
+import android.text.TextUtils;
+import android.util.Log;
+import android.util.Xml;
+
+import com.android.internal.content.PackageMonitor;
+
+import org.xmlpull.v1.XmlPullParser;
+import org.xmlpull.v1.XmlPullParserException;
+import org.xmlpull.v1.XmlSerializer;
+
+import java.io.FileInputStream;
+import java.io.FileNotFoundException;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.math.BigDecimal;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.LinkedHashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+
+/**
+ * <p>
+ * This class represents a data model for choosing a component for handing a
+ * given {@link Intent}. The model is responsible for querying the system for
+ * activities that can handle the given intent and order found activities
+ * based on historical data of previous choices. The historical data is stored
+ * in an application private file. If a client does not want to have persistent
+ * choice history the file can be omitted, thus the activities will be ordered
+ * based on historical usage for the current session.
+ * <p>
+ * </p>
+ * For each backing history file there is a singleton instance of this class. Thus,
+ * several clients that specify the same history file will share the same model. Note
+ * that if multiple clients are sharing the same model they should implement semantically
+ * equivalent functionality since setting the model intent will change the found
+ * activities and they may be inconsistent with the functionality of some of the clients.
+ * For example, choosing a share activity can be implemented by a single backing
+ * model and two different views for performing the selection. If however, one of the
+ * views is used for sharing but the other for importing, for example, then each
+ * view should be backed by a separate model.
+ * </p>
+ * <p>
+ * The way clients interact with this class is as follows:
+ * </p>
+ * <p>
+ * <pre>
+ * <code>
+ *  // Get a model and set it to a couple of clients with semantically similar function.
+ *  ActivityChooserModel dataModel =
+ *      ActivityChooserModel.get(context, "task_specific_history_file_name.xml");
+ *
+ *  ActivityChooserModelClient modelClient1 = getActivityChooserModelClient1();
+ *  modelClient1.setActivityChooserModel(dataModel);
+ *
+ *  ActivityChooserModelClient modelClient2 = getActivityChooserModelClient2();
+ *  modelClient2.setActivityChooserModel(dataModel);
+ *
+ *  // Set an intent to choose a an activity for.
+ *  dataModel.setIntent(intent);
+ * <pre>
+ * <code>
+ * </p>
+ * <p>
+ * <strong>Note:</strong> This class is thread safe.
+ * </p>
+ *
+ * @hide
+ */
+public class ActivityChooserModel extends DataSetObservable {
+
+    /**
+     * Client that utilizes an {@link ActivityChooserModel}.
+     */
+    public interface ActivityChooserModelClient {
+
+        /**
+         * Sets the {@link ActivityChooserModel}.
+         *
+         * @param dataModel The model.
+         */
+        public void setActivityChooserModel(ActivityChooserModel dataModel);
+    }
+
+    /**
+     * Defines a sorter that is responsible for sorting the activities
+     * based on the provided historical choices and an intent.
+     */
+    public interface ActivitySorter {
+
+        /**
+         * Sorts the <code>activities</code> in descending order of relevance
+         * based on previous history and an intent.
+         *
+         * @param intent The {@link Intent}.
+         * @param activities Activities to be sorted.
+         * @param historicalRecords Historical records.
+         */
+        // This cannot be done by a simple comparator since an Activity weight
+        // is computed from history. Note that Activity implements Comparable.
+        public void sort(Intent intent, List<Activity> activities,
+                List<HistoricalRecord> historicalRecords);
+    }
+
+    /**
+     * Flag for selecting debug mode.
+     */
+    private static final boolean DEBUG = false;
+
+    /**
+     * Tag used for logging.
+     */
+    private static final String LOG_TAG = ActivityChooserModel.class.getSimpleName();
+
+    /**
+     * The root tag in the history file.
+     */
+    private static final String TAG_HISTORICAL_RECORDS = "historical-records";
+
+    /**
+     * The tag for a record in the history file.
+     */
+    private static final String TAG_HISTORICAL_RECORD = "historical-record";
+
+    /**
+     * Attribute for the activity.
+     */
+    private static final String ATTRIBUTE_ACTIVITY = "activity";
+
+    /**
+     * Attribute for the choice time.
+     */
+    private static final String ATTRIBUTE_TIME = "time";
+
+    /**
+     * Attribute for the choice weight.
+     */
+    private static final String ATTRIBUTE_WEIGHT = "weight";
+
+    /**
+     * The default name of the choice history file.
+     */
+    public static final String DEFAULT_HISTORY_FILE_NAME =
+        "activity_choser_model_history.xml";
+
+    /**
+     * The default maximal length of the choice history.
+     */
+    public static final int DEFAULT_HISTORY_MAX_LENGTH = 50;
+
+    /**
+     * The amount with which to inflate a chosen activity when set as default.
+     */
+    private static final int DEFAULT_ACTIVITY_INFLATION = 5;
+
+    /**
+     * Default weight for a choice record.
+     */
+    private static final float DEFAULT_HISTORICAL_RECORD_WEIGHT = 1.0f;
+
+    /**
+     * The extension of the history file.
+     */
+    private static final String HISTORY_FILE_EXTENSION = ".xml";
+
+    /**
+     * An invalid item index.
+     */
+    private static final int INVALID_INDEX = -1;
+
+    /**
+     * Lock to guard the model registry.
+     */
+    private static final Object sRegistryLock = new Object();
+
+    /**
+     * This the registry for data models.
+     */
+    private static final Map<String, ActivityChooserModel> sDataModelRegistry =
+        new HashMap<String, ActivityChooserModel>();
+
+    /**
+     * Lock for synchronizing on this instance.
+     */
+    private final Object mInstanceLock = new Object();
+
+    /**
+     * List of activities that can handle the current intent.
+     */
+    private final List<Activity> mActivitys = new ArrayList<Activity>();
+
+    /**
+     * List with historical choice records.
+     */
+    private final List<HistoricalRecord> mHistoricalRecords = new ArrayList<HistoricalRecord>();
+
+    /**
+     * Monitor for added and removed packages.
+     */
+    private final PackageMonitor mPackageMonitor = new DataModelPackageMonitor();
+
+    /**
+     * Context for accessing resources.
+     */
+    private final Context mContext;
+
+    /**
+     * The name of the history file that backs this model.
+     */
+    private final String mHistoryFileName;
+
+    /**
+     * The intent for which a activity is being chosen.
+     */
+    private Intent mIntent;
+
+    /**
+     * The sorter for ordering activities based on intent and past choices.
+     */
+    private ActivitySorter mActivitySorter = new DefaultSorter();
+
+    /**
+     * The maximal length of the choice history.
+     */
+    private int mHistoryMaxSize = DEFAULT_HISTORY_MAX_LENGTH;
+
+    /**
+     * Flag whether choice history can be read. In general many clients can
+     * share the same data model and {@link #readHistoricalData()} may be called
+     * by arbitrary of them any number of times. Therefore, this class guarantees
+     * that the very first read succeeds and subsequent reads can be performed
+     * only after a call to {@link #persistHistoricalData()} followed by change
+     * of the share records.
+     */
+    private boolean mCanReadHistoricalData = true;
+
+    /**
+     * Flag whether the choice history was read. This is used to enforce that
+     * before calling {@link #persistHistoricalData()} a call to
+     * {@link #persistHistoricalData()} has been made. This aims to avoid a
+     * scenario in which a choice history file exits, it is not read yet and
+     * it is overwritten. Note that always all historical records are read in
+     * full and the file is rewritten. This is necessary since we need to
+     * purge old records that are outside of the sliding window of past choices.
+     */
+    private boolean mReadShareHistoryCalled = false;
+
+    /**
+     * Flag whether the choice records have changed. In general many clients can
+     * share the same data model and {@link #persistHistoricalData()} may be called
+     * by arbitrary of them any number of times. Therefore, this class guarantees
+     * that choice history will be persisted only if it has changed.
+     */
+    private boolean mHistoricalRecordsChanged = true;
+
+    /**
+     * Hander for scheduling work on client tread.
+     */
+    private final Handler mHandler = new Handler();
+
+    /**
+     * Gets the data model backed by the contents of the provided file with historical data.
+     * Note that only one data model is backed by a given file, thus multiple calls with
+     * the same file name will return the same model instance. If no such instance is present
+     * it is created.
+     * <p>
+     * <strong>Note:</strong> To use the default historical data file clients should explicitly
+     * pass as file name {@link #DEFAULT_HISTORY_FILE_NAME}. If no persistence of the choice
+     * history is desired clients should pass <code>null</code> for the file name. In such
+     * case a new model is returned for each invocation.
+     * </p>
+     *
+     * <p>
+     * <strong>Always use difference historical data files for semantically different actions.
+     * For example, sharing is different from importing.</strong>
+     * </p>
+     *
+     * @param context Context for loading resources.
+     * @param historyFileName File name with choice history, <code>null</code>
+     *        if the model should not be backed by a file. In this case the activities
+     *        will be ordered only by data from the current session.
+     *
+     * @return The model.
+     */
+    public static ActivityChooserModel get(Context context, String historyFileName) {
+        if (historyFileName == null) {
+            return new ActivityChooserModel(context, historyFileName);
+        }
+        synchronized (sRegistryLock) {
+            ActivityChooserModel dataModel = sDataModelRegistry.get(historyFileName);
+            if (dataModel == null) {
+                dataModel = new ActivityChooserModel(context, historyFileName);
+                sDataModelRegistry.put(historyFileName, dataModel);
+            }
+            return dataModel;
+        }
+    }
+
+    /**
+     * Creates a new instance.
+     *
+     * @param context Context for loading resources.
+     * @param historyFileName The history XML file.
+     */
+    private ActivityChooserModel(Context context, String historyFileName) {
+        mContext = context.getApplicationContext();
+        if (!TextUtils.isEmpty(historyFileName)
+                && !historyFileName.endsWith(HISTORY_FILE_EXTENSION)) {
+            mHistoryFileName = historyFileName + HISTORY_FILE_EXTENSION;
+        } else {
+            mHistoryFileName = historyFileName;
+        }
+        mPackageMonitor.register(mContext, true);
+    }
+
+    /**
+     * Sets an intent for which to choose a activity.
+     * <p>
+     * <strong>Note:</strong> Clients must set only semantically similar
+     * intents for each data model.
+     * <p>
+     *
+     * @param intent The intent.
+     */
+    public void setIntent(Intent intent) {
+        synchronized (mInstanceLock) {
+            if (mIntent == intent) {
+                return;
+            }
+            mIntent = intent;
+            loadActivitiesLocked();
+        }
+    }
+
+    /**
+     * Gets the intent for which a activity is being chosen.
+     *
+     * @return The intent.
+     */
+    public Intent getIntent() {
+        synchronized (mInstanceLock) {
+            return mIntent;
+        }
+    }
+
+    /**
+     * Gets the number of activities that can handle the intent.
+     *
+     * @return The activity count.
+     *
+     * @see #setIntent(Intent)
+     */
+    public int getActivityCount() {
+        synchronized (mInstanceLock) {
+            return mActivitys.size();
+        }
+    }
+
+    /**
+     * Gets an activity at a given index.
+     *
+     * @return The activity.
+     *
+     * @see Activity
+     * @see #setIntent(Intent)
+     */
+    public ResolveInfo getActivity(int index) {
+        synchronized (mInstanceLock) {
+            return mActivitys.get(index).resolveInfo;
+        }
+    }
+
+    /**
+     * Gets the index of a the given activity.
+     *
+     * @param activity The activity index.
+     *
+     * @return The index if found, -1 otherwise.
+     */
+    public int getActivityIndex(ResolveInfo activity) {
+        List<Activity> activities = mActivitys;
+        final int activityCount = activities.size();
+        for (int i = 0; i < activityCount; i++) {
+            Activity currentActivity = activities.get(i);
+            if (currentActivity.resolveInfo == activity) {
+                return i;
+            }
+        }
+        return INVALID_INDEX;
+    }
+
+    /**
+     * Chooses a activity to handle the current intent. This will result in
+     * adding a historical record for that action and construct intent with
+     * its component name set such that it can be immediately started by the
+     * client.
+     * <p>
+     * <strong>Note:</strong> By calling this method the client guarantees
+     * that the returned intent will be started. This intent is returned to
+     * the client solely to let additional customization before the start.
+     * </p>
+     *
+     * @return Whether adding succeeded.
+     *
+     * @see HistoricalRecord
+     */
+    public Intent chooseActivity(int index) {
+        Activity chosenActivity = mActivitys.get(index);
+        Activity defaultActivity = mActivitys.get(0);
+
+        ComponentName chosenName = new ComponentName(
+                chosenActivity.resolveInfo.activityInfo.packageName,
+                chosenActivity.resolveInfo.activityInfo.name);
+        HistoricalRecord historicalRecord = new HistoricalRecord(chosenName,
+                System.currentTimeMillis(), DEFAULT_HISTORICAL_RECORD_WEIGHT);
+        addHisoricalRecord(historicalRecord);
+
+        Intent choiceIntent = new Intent(mIntent);
+        choiceIntent.setComponent(chosenName);
+
+        return choiceIntent;
+    }
+
+    /**
+     * Gets the default activity, The default activity is defined as the one
+     * with highest rank i.e. the first one in the list of activities that can
+     * handle the intent.
+     *
+     * @return The default activity, <code>null</code> id not activities.
+     *
+     * @see #getActivity(int)
+     */
+    public ResolveInfo getDefaultActivity() {
+        synchronized (mInstanceLock) {
+            if (!mActivitys.isEmpty()) {
+                return mActivitys.get(0).resolveInfo;
+            }
+        }
+        return null;
+    }
+
+    /**
+     * Sets the default activity. The default activity is set by adding a
+     * historical record with weight high enough that this activity will
+     * become the highest ranked. Such a strategy guarantees that the default
+     * will eventually change if not used. Also the weight of the record for
+     * setting a default is inflated with a constant amount to guarantee that
+     * it will stay as default for awhile.
+     *
+     * @param index The index of the activity to set as default.
+     */
+    public void setDefaultActivity(int index) {
+        Activity newDefaultActivity = mActivitys.get(index);
+        Activity oldDefaultActivity = mActivitys.get(0);
+
+        final float weight;
+        if (oldDefaultActivity != null) {
+            // Add a record with weight enough to boost the chosen at the top.
+            weight = oldDefaultActivity.weight - newDefaultActivity.weight
+                + DEFAULT_ACTIVITY_INFLATION;
+        } else {
+            weight = DEFAULT_HISTORICAL_RECORD_WEIGHT;
+        }
+
+        ComponentName defaultName = new ComponentName(
+                newDefaultActivity.resolveInfo.activityInfo.packageName,
+                newDefaultActivity.resolveInfo.activityInfo.name);
+        HistoricalRecord historicalRecord = new HistoricalRecord(defaultName,
+                System.currentTimeMillis(), weight);
+        addHisoricalRecord(historicalRecord);
+    }
+
+    /**
+     * Reads the history data from the backing file if the latter
+     * was provided. Calling this method more than once before a call
+     * to {@link #persistHistoricalData()} has been made has no effect.
+     * <p>
+     * <strong>Note:</strong> Historical data is read asynchronously and
+     *       as soon as the reading is completed any registered
+     *       {@link DataSetObserver}s will be notified. Also no historical
+     *       data is read until this method is invoked.
+     * <p>
+     */
+    public void readHistoricalData() {
+        synchronized (mInstanceLock) {
+            if (!mCanReadHistoricalData || !mHistoricalRecordsChanged) {
+                return;
+            }
+            mCanReadHistoricalData = false;
+            mReadShareHistoryCalled = true;
+            if (!TextUtils.isEmpty(mHistoryFileName)) {
+                AsyncTask.SERIAL_EXECUTOR.execute(new HistoryLoader());
+            }
+        }
+    }
+
+    /**
+     * Persists the history data to the backing file if the latter
+     * was provided. Calling this method before a call to {@link #readHistoricalData()}
+     * throws an exception. Calling this method more than one without choosing an
+     * activity has not effect.
+     *
+     * @throws IllegalStateException If this method is called before a call to
+     *         {@link #readHistoricalData()}.
+     */
+    public void persistHistoricalData() {
+        synchronized (mInstanceLock) {
+            if (!mReadShareHistoryCalled) {
+                throw new IllegalStateException("No preceding call to #readHistoricalData");
+            }
+            if (!mHistoricalRecordsChanged) {
+                return;
+            }
+            mHistoricalRecordsChanged = false;
+            mCanReadHistoricalData = true;
+            if (!TextUtils.isEmpty(mHistoryFileName)) {
+                AsyncTask.SERIAL_EXECUTOR.execute(new HistoryPersister());
+            }
+        }
+    }
+
+    /**
+     * Sets the sorter for ordering activities based on historical data and an intent.
+     *
+     * @param activitySorter The sorter.
+     *
+     * @see ActivitySorter
+     */
+    public void setActivitySorter(ActivitySorter activitySorter) {
+        synchronized (mInstanceLock) {
+            if (mActivitySorter == activitySorter) {
+                return;
+            }
+            mActivitySorter = activitySorter;
+            sortActivities();
+        }
+    }
+
+    /**
+     * Sorts the activities based on history and an intent. If
+     * a sorter is not specified this a default implementation is used.
+     *
+     * @see #setActivitySorter(ActivitySorter)
+     */
+    private void sortActivities() {
+        synchronized (mInstanceLock) {
+            if (mActivitySorter != null && !mActivitys.isEmpty()) {
+                mActivitySorter.sort(mIntent, mActivitys,
+                        Collections.unmodifiableList(mHistoricalRecords));
+                notifyChanged();
+            }
+        }
+    }
+
+    /**
+     * Sets the maximal size of the historical data. Defaults to
+     * {@link #DEFAULT_HISTORY_MAX_LENGTH}
+     * <p>
+     *   <strong>Note:</strong> Setting this property will immediately
+     *   enforce the specified max history size by dropping enough old
+     *   historical records to enforce the desired size. Thus, any
+     *   records that exceed the history size will be discarded and
+     *   irreversibly lost.
+     * </p>
+     *
+     * @param historyMaxSize The max history size.
+     */
+    public void setHistoryMaxSize(int historyMaxSize) {
+        synchronized (mInstanceLock) {
+            if (mHistoryMaxSize == historyMaxSize) {
+                return;
+            }
+            mHistoryMaxSize = historyMaxSize;
+            pruneExcessiveHistoricalRecordsLocked();
+            sortActivities();
+        }
+    }
+
+    /**
+     * Gets the history max size.
+     *
+     * @return The history max size.
+     */
+    public int getHistoryMaxSize() {
+        synchronized (mInstanceLock) {
+            return mHistoryMaxSize;
+        }
+    }
+
+    @Override
+    protected void finalize() throws Throwable {
+        super.finalize();
+        mPackageMonitor.unregister();
+    }
+
+    /**
+     * Adds a historical record.
+     *
+     * @param historicalRecord The record to add.
+     * @return True if the record was added.
+     */
+    private boolean addHisoricalRecord(HistoricalRecord historicalRecord) {
+        synchronized (mInstanceLock) {
+            final boolean added = mHistoricalRecords.add(historicalRecord);
+            if (added) {
+                mHistoricalRecordsChanged = true;
+                pruneExcessiveHistoricalRecordsLocked();
+                sortActivities();
+            }
+            return added;
+        }
+    }
+
+    /**
+     * Prunes older excessive records to guarantee {@link #mHistoryMaxSize}.
+     */
+    private void pruneExcessiveHistoricalRecordsLocked() {
+        List<HistoricalRecord> choiceRecords = mHistoricalRecords;
+        final int pruneCount = choiceRecords.size() - mHistoryMaxSize;
+        if (pruneCount <= 0) {
+            return;
+        }
+        mHistoricalRecordsChanged = true;
+        for (int i = 0; i < pruneCount; i++) {
+            HistoricalRecord prunedRecord = choiceRecords.remove(0);
+            if (DEBUG) {
+                Log.i(LOG_TAG, "Pruned: " + prunedRecord);
+            }
+        }
+    }
+
+    /**
+     * Loads the activities.
+     */
+    private void loadActivitiesLocked() {
+        mActivitys.clear();
+        if (mIntent != null) {
+            List<ResolveInfo> resolveInfos =
+                mContext.getPackageManager().queryIntentActivities(mIntent, 0);
+            final int resolveInfoCount = resolveInfos.size();
+            for (int i = 0; i < resolveInfoCount; i++) {
+                ResolveInfo resolveInfo = resolveInfos.get(i);
+                mActivitys.add(new Activity(resolveInfo));
+            }
+            sortActivities();
+        } else {
+            notifyChanged();
+        }
+    }
+
+    /**
+     * Prunes historical records for a package that goes away.
+     *
+     * @param packageName The name of the package that goes away.
+     */
+    private void pruneHistoricalRecordsForPackageLocked(String packageName) {
+        boolean recordsRemoved = false;
+
+        List<HistoricalRecord> historicalRecords = mHistoricalRecords;
+        for (int i = 0; i < historicalRecords.size(); i++) {
+            HistoricalRecord historicalRecord = historicalRecords.get(i);
+            String recordPackageName = historicalRecord.activity.getPackageName();
+            if (recordPackageName.equals(packageName)) {
+                historicalRecords.remove(historicalRecord);
+                recordsRemoved = true;
+            }
+        }
+
+        if (recordsRemoved) {
+            mHistoricalRecordsChanged = true;
+            sortActivities();
+        }
+    }
+
+    /**
+     * Represents a record in the history.
+     */
+    public final static class HistoricalRecord {
+
+        /**
+         * The activity name.
+         */
+        public final ComponentName activity;
+
+        /**
+         * The choice time.
+         */
+        public final long time;
+
+        /**
+         * The record weight.
+         */
+        public final float weight;
+
+        /**
+         * Creates a new instance.
+         *
+         * @param activityName The activity component name flattened to string.
+         * @param time The time the activity was chosen.
+         * @param weight The weight of the record.
+         */
+        public HistoricalRecord(String activityName, long time, float weight) {
+            this(ComponentName.unflattenFromString(activityName), time, weight);
+        }
+
+        /**
+         * Creates a new instance.
+         *
+         * @param activityName The activity name.
+         * @param time The time the activity was chosen.
+         * @param weight The weight of the record.
+         */
+        public HistoricalRecord(ComponentName activityName, long time, float weight) {
+            this.activity = activityName;
+            this.time = time;
+            this.weight = weight;
+        }
+
+        @Override
+        public int hashCode() {
+            final int prime = 31;
+            int result = 1;
+            result = prime * result + ((activity == null) ? 0 : activity.hashCode());
+            result = prime * result + (int) (time ^ (time >>> 32));
+            result = prime * result + Float.floatToIntBits(weight);
+            return result;
+        }
+
+        @Override
+        public boolean equals(Object obj) {
+            if (this == obj) {
+                return true;
+            }
+            if (obj == null) {
+                return false;
+            }
+            if (getClass() != obj.getClass()) {
+                return false;
+            }
+            HistoricalRecord other = (HistoricalRecord) obj;
+            if (activity == null) {
+                if (other.activity != null) {
+                    return false;
+                }
+            } else if (!activity.equals(other.activity)) {
+                return false;
+            }
+            if (time != other.time) {
+                return false;
+            }
+            if (Float.floatToIntBits(weight) != Float.floatToIntBits(other.weight)) {
+                return false;
+            }
+            return true;
+        }
+
+        @Override
+        public String toString() {
+            StringBuilder builder = new StringBuilder();
+            builder.append("[");
+            builder.append("; activity:").append(activity);
+            builder.append("; time:").append(time);
+            builder.append("; weight:").append(new BigDecimal(weight));
+            builder.append("]");
+            return builder.toString();
+        }
+    }
+
+    /**
+     * Represents an activity.
+     */
+    public final class Activity implements Comparable<Activity> {
+
+        /**
+         * The {@link ResolveInfo} of the activity.
+         */
+        public final ResolveInfo resolveInfo;
+
+        /**
+         * Weight of the activity. Useful for sorting.
+         */
+        public float weight;
+
+        /**
+         * Creates a new instance.
+         *
+         * @param resolveInfo activity {@link ResolveInfo}.
+         */
+        public Activity(ResolveInfo resolveInfo) {
+            this.resolveInfo = resolveInfo;
+        }
+
+        @Override
+        public int hashCode() {
+            return 31 + Float.floatToIntBits(weight);
+        }
+
+        @Override
+        public boolean equals(Object obj) {
+            if (this == obj) {
+                return true;
+            }
+            if (obj == null) {
+                return false;
+            }
+            if (getClass() != obj.getClass()) {
+                return false;
+            }
+            Activity other = (Activity) obj;
+            if (Float.floatToIntBits(weight) != Float.floatToIntBits(other.weight)) {
+                return false;
+            }
+            return true;
+        }
+
+        public int compareTo(Activity another) {
+             return  Float.floatToIntBits(another.weight) - Float.floatToIntBits(weight);
+        }
+
+        @Override
+        public String toString() {
+            StringBuilder builder = new StringBuilder();
+            builder.append("[");
+            builder.append("resolveInfo:").append(resolveInfo.toString());
+            builder.append("; weight:").append(new BigDecimal(weight));
+            builder.append("]");
+            return builder.toString();
+        }
+    }
+
+    /**
+     * Default activity sorter implementation.
+     */
+    private final class DefaultSorter implements ActivitySorter {
+        private static final float WEIGHT_DECAY_COEFFICIENT = 0.95f;
+
+        private final Map<String, Activity> mPackageNameToActivityMap =
+            new HashMap<String, Activity>();
+
+        public void sort(Intent intent, List<Activity> activities,
+                List<HistoricalRecord> historicalRecords) {
+            Map<String, Activity> packageNameToActivityMap =
+                mPackageNameToActivityMap;
+            packageNameToActivityMap.clear();
+
+            final int activityCount = activities.size();
+            for (int i = 0; i < activityCount; i++) {
+                Activity activity = activities.get(i);
+                activity.weight = 0.0f;
+                String packageName = activity.resolveInfo.activityInfo.packageName;
+                packageNameToActivityMap.put(packageName, activity);
+            }
+
+            final int lastShareIndex = historicalRecords.size() - 1;
+            float nextRecordWeight = 1;
+            for (int i = lastShareIndex; i >= 0; i--) {
+                HistoricalRecord historicalRecord = historicalRecords.get(i);
+                String packageName = historicalRecord.activity.getPackageName();
+                Activity activity = packageNameToActivityMap.get(packageName);
+                activity.weight += historicalRecord.weight * nextRecordWeight;
+                nextRecordWeight = nextRecordWeight * WEIGHT_DECAY_COEFFICIENT;
+            }
+
+            Collections.sort(activities);
+
+            if (DEBUG) {
+                for (int i = 0; i < activityCount; i++) {
+                    Log.i(LOG_TAG, "Sorted: " + activities.get(i));
+                }
+            }
+        }
+    }
+
+    /**
+     * Command for reading the historical records from a file off the UI thread.
+     */
+    private final class HistoryLoader implements Runnable {
+
+       public void run() {
+            FileInputStream fis = null;
+            try {
+                fis = mContext.openFileInput(mHistoryFileName);
+            } catch (FileNotFoundException fnfe) {
+                if (DEBUG) {
+                    Log.i(LOG_TAG, "Could not open historical records file: " + mHistoryFileName);
+                }
+                return;
+            }
+            try {
+                XmlPullParser parser = Xml.newPullParser();
+                parser.setInput(fis, null);
+
+                int type = XmlPullParser.START_DOCUMENT;
+                while (type != XmlPullParser.END_DOCUMENT && type != XmlPullParser.START_TAG) {
+                    type = parser.next();
+                }
+
+                if (!TAG_HISTORICAL_RECORDS.equals(parser.getName())) {
+                    throw new XmlPullParserException("Share records file does not start with "
+                            + TAG_HISTORICAL_RECORDS + " tag.");
+                }
+
+                List<HistoricalRecord> readRecords = new ArrayList<HistoricalRecord>();
+
+                while (true) {
+                    type = parser.next();
+                    if (type == XmlPullParser.END_DOCUMENT) {
+                        break;
+                    }
+                    if (type == XmlPullParser.END_TAG || type == XmlPullParser.TEXT) {
+                        continue;
+                    }
+                    String nodeName = parser.getName();
+                    if (!TAG_HISTORICAL_RECORD.equals(nodeName)) {
+                        throw new XmlPullParserException("Share records file not well-formed.");
+                    }
+
+                    String activity = parser.getAttributeValue(null, ATTRIBUTE_ACTIVITY);
+                    final long time =
+                        Long.parseLong(parser.getAttributeValue(null, ATTRIBUTE_TIME));
+                    final float weight =
+                        Float.parseFloat(parser.getAttributeValue(null, ATTRIBUTE_WEIGHT));
+
+                    HistoricalRecord readRecord = new HistoricalRecord(activity, time,
+                            weight);
+                    readRecords.add(readRecord);
+
+                    if (DEBUG) {
+                        Log.i(LOG_TAG, "Read " + readRecord.toString());
+                    }
+                }
+
+                if (DEBUG) {
+                    Log.i(LOG_TAG, "Read " + readRecords.size() + " historical records.");
+                }
+
+                synchronized (mInstanceLock) {
+                    Set<HistoricalRecord> uniqueShareRecords =
+                        new LinkedHashSet<HistoricalRecord>(readRecords);
+
+                    // Make sure no duplicates. Example: Read a file with
+                    // one record, add one record, persist the two records,
+                    // add a record, read the persisted records - the
+                    // read two records should not be added again.
+                    List<HistoricalRecord> historicalRecords = mHistoricalRecords;
+                    final int historicalRecordsCount = historicalRecords.size();
+                    for (int i = historicalRecordsCount - 1; i >= 0; i--) {
+                        HistoricalRecord historicalRecord = historicalRecords.get(i);
+                        uniqueShareRecords.add(historicalRecord);
+                    }
+
+                    if (historicalRecords.size() == uniqueShareRecords.size()) {
+                        return;
+                    }
+
+                    // Make sure the oldest records go to the end.
+                    historicalRecords.clear();
+                    historicalRecords.addAll(uniqueShareRecords);
+
+                    mHistoricalRecordsChanged = true;
+
+                    // Do this on the client thread since the client may be on the UI
+                    // thread, wait for data changes which happen during sorting, and
+                    // perform UI modification based on the data change.
+                    mHandler.post(new Runnable() {
+                        public void run() {
+                            pruneExcessiveHistoricalRecordsLocked();
+                            sortActivities();
+                        }
+                    });
+                }
+            } catch (XmlPullParserException xppe) {
+                Log.e(LOG_TAG, "Error reading historical recrod file: " + mHistoryFileName, xppe);
+            } catch (IOException ioe) {
+                Log.e(LOG_TAG, "Error reading historical recrod file: " + mHistoryFileName, ioe);
+            } finally {
+                if (fis != null) {
+                    try {
+                        fis.close();
+                    } catch (IOException ioe) {
+                        /* ignore */
+                    }
+                }
+            }
+        }
+    }
+
+    /**
+     * Command for persisting the historical records to a file off the UI thread.
+     */
+    private final class HistoryPersister implements Runnable {
+
+        public void run() {
+            FileOutputStream fos = null;
+            List<HistoricalRecord> records = null;
+
+            synchronized (mInstanceLock) {
+                records = new ArrayList<HistoricalRecord>(mHistoricalRecords);
+            }
+
+            try {
+                fos = mContext.openFileOutput(mHistoryFileName, Context.MODE_PRIVATE);
+            } catch (FileNotFoundException fnfe) {
+                Log.e(LOG_TAG, "Error writing historical recrod file: " + mHistoryFileName, fnfe);
+                return;
+            }
+
+            XmlSerializer serializer = Xml.newSerializer();
+
+            try {
+                serializer.setOutput(fos, null);
+                serializer.startDocument("UTF-8", true);
+                serializer.startTag(null, TAG_HISTORICAL_RECORDS);
+
+                final int recordCount = records.size();
+                for (int i = 0; i < recordCount; i++) {
+                    HistoricalRecord record = records.remove(0);
+                    serializer.startTag(null, TAG_HISTORICAL_RECORD);
+                    serializer.attribute(null, ATTRIBUTE_ACTIVITY, record.activity.flattenToString());
+                    serializer.attribute(null, ATTRIBUTE_TIME, String.valueOf(record.time));
+                    serializer.attribute(null, ATTRIBUTE_WEIGHT, String.valueOf(record.weight));
+                    serializer.endTag(null, TAG_HISTORICAL_RECORD);
+                    if (DEBUG) {
+                        Log.i(LOG_TAG, "Wrote " + record.toString());
+                    }
+                }
+
+                serializer.endTag(null, TAG_HISTORICAL_RECORDS);
+                serializer.endDocument();
+
+                if (DEBUG) {
+                    Log.i(LOG_TAG, "Wrote " + recordCount + " historical records.");
+                }
+            } catch (IllegalArgumentException iae) {
+                Log.e(LOG_TAG, "Error writing historical recrod file: " + mHistoryFileName, iae);
+            } catch (IllegalStateException ise) {
+                Log.e(LOG_TAG, "Error writing historical recrod file: " + mHistoryFileName, ise);
+            } catch (IOException ioe) {
+                Log.e(LOG_TAG, "Error writing historical recrod file: " + mHistoryFileName, ioe);
+            } finally {
+                if (fos != null) {
+                    try {
+                        fos.close();
+                    } catch (IOException e) {
+                        /* ignore */
+                    }
+                }
+            }
+        }
+    }
+
+    /**
+     * Keeps in sync the historical records and activities with the installed applications.
+     */
+    private final class DataModelPackageMonitor extends PackageMonitor {
+
+        @Override
+        public void onPackageAdded(String packageName, int uid) {
+            synchronized (mInstanceLock) {
+                loadActivitiesLocked();
+            }
+        }
+
+        @Override
+        public void onPackageAppeared(String packageName, int reason) {
+            synchronized (mInstanceLock) {
+                loadActivitiesLocked();
+            }
+        }
+
+        @Override
+        public void onPackageRemoved(String packageName, int uid) {
+            synchronized (mInstanceLock) {
+                pruneHistoricalRecordsForPackageLocked(packageName);
+                loadActivitiesLocked();
+            }
+        }
+
+        @Override
+        public void onPackageDisappeared(String packageName, int reason) {
+            synchronized (mInstanceLock) {
+                pruneHistoricalRecordsForPackageLocked(packageName);
+                loadActivitiesLocked();
+            }
+        }
+    }
+}
diff --git a/core/java/android/widget/ActivityChooserView.java b/core/java/android/widget/ActivityChooserView.java
new file mode 100644
index 0000000..2fe8162
--- /dev/null
+++ b/core/java/android/widget/ActivityChooserView.java
@@ -0,0 +1,765 @@
+/*
+ * Copyright (C) 2011 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package android.widget;
+
+import android.app.AlertDialog;
+import android.app.AlertDialog.Builder;
+import android.content.Context;
+import android.content.DialogInterface;
+import android.content.Intent;
+import android.content.pm.PackageManager;
+import android.content.pm.ResolveInfo;
+import android.content.res.TypedArray;
+import android.database.DataSetObserver;
+import android.graphics.Canvas;
+import android.graphics.drawable.Drawable;
+import android.os.Debug;
+import android.util.AttributeSet;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.ViewGroup;
+import android.widget.ActivityChooserModel.ActivityChooserModelClient;
+
+import com.android.internal.R;
+
+/**
+ * This class is a view for choosing an activity for handling a given {@link Intent}.
+ * <p>
+ * The view is composed of two adjacent buttons:
+ * <ul>
+ * <li>
+ * The left button is an immediate action and allows one click activity choosing.
+ * Tapping this button immediately executes the intent without requiring any further
+ * user input. Long press on this button shows a popup for changing the default
+ * activity.
+ * </li>
+ * <li>
+ * The right button is an overflow action and provides an optimized menu
+ * of additional activities. Tapping this button shows a popup anchored to this
+ * view, listing the most frequently used activities. This list is initially
+ * limited to a small number of items in frequency used order. The last item,
+ * "Show all..." serves as an affordance to display all available activities.
+ * </li>
+ * </ul>
+ * </p>
+ * </p>
+ * This view is backed by a {@link ActivityChooserModel}. Calling {@link #showPopup()}
+ * while this view is attached to the view hierarchy will show a popup with
+ * activities while if the view is not attached it will show a dialog.
+ * </p>
+ *
+ * @hide
+ */
+public class ActivityChooserView extends ViewGroup implements ActivityChooserModelClient {
+
+    /**
+     * An adapter for displaying the activities in an {@link AdapterView}.
+     */
+    private final ActivityChooserViewAdapter mAdapter;
+
+    /**
+     * Implementation of various interfaces to avoid publishing them in the APIs.
+     */
+    private final Callbacks mCallbacks;
+
+    /**
+     * The content of this view.
+     */
+    private final LinearLayout mActivityChooserContent;
+
+    /**
+     * The expand activities action button;
+     */
+    private final ImageButton mExpandActivityOverflowButton;
+
+    /**
+     * The default activities action button;
+     */
+    private final ImageButton mDefaultActionButton;
+
+    /**
+     * The header for handlers list.
+     */
+    private final View mListHeaderView;
+
+    /**
+     * The footer for handlers list.
+     */
+    private final View mListFooterView;
+
+    /**
+     * The title of the header view.
+     */
+    private TextView mListHeaderViewTitle;
+
+    /**
+     * The title for expanding the activities list.
+     */
+    private final String mListHeaderViewTitleSelectDefault;
+
+    /**
+     * The title if no activity exist.
+     */
+    private final String mListHeaderViewTitleNoActivities;
+
+    /**
+     * Popup window for showing the activity overflow list.
+     */
+    private ListPopupWindow mListPopupWindow;
+
+    /**
+     * Alert dialog for showing the activity overflow list.
+     */
+    private AlertDialog mAlertDialog;
+
+    /**
+     * Listener for the dismissal of the popup/alert.
+     */
+    private PopupWindow.OnDismissListener mOnDismissListener;
+
+    /**
+     * Flag whether a default activity currently being selected.
+     */
+    private boolean mIsSelectingDefaultActivity;
+
+    /**
+     * The count of activities in the popup.
+     */
+    private int mInitialActivityCount = ActivityChooserViewAdapter.MAX_ACTIVITY_COUNT_DEFAULT;
+
+    /**
+     * Flag whether this view is attached to a window.
+     */
+    private boolean mIsAttachedToWindow;
+
+    /**
+     * Flag whether this view is showing an alert dialog.
+     */
+    private boolean mIsShowingAlertDialog;
+
+    /**
+     * Flag whether this view is showing a popup window.
+     */
+    private boolean mIsShowingPopuWindow;
+
+    /**
+     * Create a new instance.
+     *
+     * @param context The application environment.
+     */
+    public ActivityChooserView(Context context) {
+        this(context, null);
+    }
+
+    /**
+     * Create a new instance.
+     *
+     * @param context The application environment.
+     * @param attrs A collection of attributes.
+     */
+    public ActivityChooserView(Context context, AttributeSet attrs) {
+        this(context, attrs, R.attr.actionButtonStyle);
+    }
+
+    /**
+     * Create a new instance.
+     *
+     * @param context The application environment.
+     * @param attrs A collection of attributes.
+     * @param defStyle The default style to apply to this view.
+     */
+    public ActivityChooserView(Context context, AttributeSet attrs, int defStyle) {
+        super(context, attrs, defStyle);
+
+        TypedArray attributesArray = context.obtainStyledAttributes(attrs,
+                R.styleable.ActivityChooserView, defStyle, 0);
+
+        mInitialActivityCount = attributesArray.getInt(
+                R.styleable.ActivityChooserView_initialActivityCount,
+                ActivityChooserViewAdapter.MAX_ACTIVITY_COUNT_DEFAULT);
+
+        Drawable expandActivityOverflowButtonDrawable = attributesArray.getDrawable(
+                R.styleable.ActivityChooserView_expandActivityOverflowButtonDrawable);
+
+        LayoutInflater inflater = (LayoutInflater) context.getSystemService(
+                Context.LAYOUT_INFLATER_SERVICE);
+        inflater.inflate(R.layout.activity_chooser_view, this, true);
+
+        mCallbacks = new Callbacks();
+
+        mActivityChooserContent = (LinearLayout) findViewById(R.id.activity_chooser_view_content);
+
+        mDefaultActionButton = (ImageButton) findViewById(R.id.default_activity_button);
+        mDefaultActionButton.setOnClickListener(mCallbacks);
+        mDefaultActionButton.setOnLongClickListener(mCallbacks);
+
+        mExpandActivityOverflowButton = (ImageButton) findViewById(R.id.expand_activities_button);
+        mExpandActivityOverflowButton.setOnClickListener(mCallbacks);
+        mExpandActivityOverflowButton.setBackgroundDrawable(expandActivityOverflowButtonDrawable);
+
+        mListHeaderView = inflater.inflate(R.layout.activity_chooser_list_header, null);
+        mListFooterView = inflater.inflate(R.layout.activity_chooser_list_footer, null);
+
+        mListHeaderViewTitle = (TextView) mListHeaderView.findViewById(R.id.title);
+        mListHeaderViewTitleSelectDefault = context.getString(
+                R.string.activity_chooser_view_select_default);
+        mListHeaderViewTitleNoActivities = context.getString(
+                R.string.activity_chooser_view_no_activities);
+
+        mAdapter = new ActivityChooserViewAdapter();
+        mAdapter.registerDataSetObserver(new DataSetObserver() {
+            @Override
+            public void onChanged() {
+                super.onChanged();
+                updateButtons();
+            }
+        });
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    public void setActivityChooserModel(ActivityChooserModel dataModel) {
+        mAdapter.setDataModel(dataModel);
+        if (isShowingPopup()) {
+            dismissPopup();
+            showPopup();
+        }
+    }
+
+    /**
+     * Sets the background for the button that expands the activity
+     * overflow list.
+     *
+     * <strong>Note:</strong> Clients would like to set this drawable
+     * as a clue about the action the chosen activity will perform. For
+     * example, if share activity is to be chosen the drawable should
+     * give a clue that sharing is to be performed.
+     *
+     * @param drawable The drawable.
+     */
+    public void setExpandActivityOverflowButtonDrawable(Drawable drawable) {
+        mExpandActivityOverflowButton.setBackgroundDrawable(drawable);
+    }
+
+    /**
+     * Shows the popup window with activities.
+     *
+     * @return True if the popup was shown, false if already showing.
+     */
+    public boolean showPopup() {
+        if (isShowingPopup()) {
+            return false;
+        }
+        mIsSelectingDefaultActivity = false;
+        showPopupUnchecked(mInitialActivityCount);
+        return true;
+    }
+
+    /**
+     * Shows the popup no matter if it was already showing.
+     *
+     * @param maxActivityCount The max number of activities to display.
+     */
+    private void showPopupUnchecked(int maxActivityCount) {
+        mAdapter.setMaxActivityCount(maxActivityCount);
+        if (mIsSelectingDefaultActivity) {
+            if (mAdapter.getActivityCount() > 0) {
+                mListHeaderViewTitle.setText(mListHeaderViewTitleSelectDefault);
+            } else {
+                mListHeaderViewTitle.setText(mListHeaderViewTitleNoActivities);
+            }
+            mAdapter.setHeaderView(mListHeaderView);
+        } else {
+            mAdapter.setHeaderView(null);
+        }
+
+        if (mAdapter.getActivityCount() > maxActivityCount + 1) {
+            mAdapter.setFooterView(mListFooterView);
+        } else {
+            mAdapter.setFooterView(null);
+        }
+
+        if (!mIsAttachedToWindow || mIsShowingAlertDialog) {
+            AlertDialog alertDialog = getAlertDilalog();
+            if (!alertDialog.isShowing()) {
+                alertDialog.setCustomTitle(this);
+                alertDialog.show();
+                mIsShowingAlertDialog = true;
+            }
+        } else {
+            ListPopupWindow popupWindow = getListPopupWindow();
+            if (!popupWindow.isShowing()) {
+                popupWindow.setContentWidth(mAdapter.measureContentWidth());
+                popupWindow.show();
+                mIsShowingPopuWindow = true;
+            }
+        }
+    }
+
+    /**
+     * Dismisses the popup window with activities.
+     *
+     * @return True if dismissed, false if already dismissed.
+     */
+    public boolean dismissPopup() {
+        if (!isShowingPopup()) {
+            return false;
+        }
+        if (mIsShowingAlertDialog) {
+            getAlertDilalog().dismiss();
+        } else if (mIsShowingPopuWindow) {
+            getListPopupWindow().dismiss();
+        }
+        return true;
+    }
+
+    /**
+     * Gets whether the popup window with activities is shown.
+     *
+     * @return True if the popup is shown.
+     */
+    public boolean isShowingPopup() {
+        if (mIsShowingAlertDialog) {
+            return getAlertDilalog().isShowing();
+        } else if (mIsShowingPopuWindow) {
+            return getListPopupWindow().isShowing();
+        }
+        return false;
+    }
+
+    @Override
+    protected void onAttachedToWindow() {
+        super.onAttachedToWindow();
+        ActivityChooserModel dataModel = mAdapter.getDataModel();
+        if (dataModel != null) {
+            dataModel.readHistoricalData();
+        }
+        mIsAttachedToWindow = true;
+    }
+
+    @Override
+    protected void onDetachedFromWindow() {
+        super.onDetachedFromWindow();
+        ActivityChooserModel dataModel = mAdapter.getDataModel();
+        if (dataModel != null) {
+            dataModel.persistHistoricalData();
+        }
+        mIsAttachedToWindow = false;
+    }
+
+    @Override
+    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
+        mActivityChooserContent.measure(widthMeasureSpec, heightMeasureSpec);
+        setMeasuredDimension(mActivityChooserContent.getMeasuredWidth(),
+                mActivityChooserContent.getMeasuredHeight());
+    }
+
+    @Override
+    protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
+        mActivityChooserContent.layout(left, top, right, bottom);
+        if (mIsShowingPopuWindow) {
+            if (isShown()) {
+                showPopupUnchecked(mAdapter.getMaxActivityCount());
+            } else {
+                dismissPopup();
+            }
+        }
+    }
+
+    @Override
+    protected void onDraw(Canvas canvas) {
+        mActivityChooserContent.onDraw(canvas);
+    }
+
+    public ActivityChooserModel getDataModel() {
+        return mAdapter.getDataModel();
+    }
+
+    /**
+     * Sets a listener to receive a callback when the popup is dismissed.
+     *
+     * @param listener The listener to be notified.
+     */
+    public void setOnDismissListener(PopupWindow.OnDismissListener listener) {
+        mOnDismissListener = listener;
+    }
+
+    /**
+     * Sets the initial count of items shown in the activities popup
+     * i.e. the items before the popup is expanded. This is an upper
+     * bound since it is not guaranteed that such number of intent
+     * handlers exist.
+     *
+     * @param itemCount The initial popup item count.
+     */
+    public void setInitialActivityCount(int itemCount) {
+        mInitialActivityCount = itemCount;
+    }
+
+    /**
+     * Gets the list popup window which is lazily initialized.
+     *
+     * @return The popup.
+     */
+    private ListPopupWindow getListPopupWindow() {
+        if (mListPopupWindow == null) {
+            mListPopupWindow = new ListPopupWindow(getContext());
+            mListPopupWindow.setAdapter(mAdapter);
+            mListPopupWindow.setAnchorView(ActivityChooserView.this);
+            mListPopupWindow.setModal(true);
+            mListPopupWindow.setOnItemClickListener(mCallbacks);
+            mListPopupWindow.setOnDismissListener(mCallbacks);
+        }
+        return mListPopupWindow;
+    }
+
+    /**
+     * Gets the alert dialog which is lazily initialized.
+     *
+     * @return The popup.
+     */
+    private AlertDialog getAlertDilalog() {
+        if (mAlertDialog == null) {
+            Builder builder = new Builder(getContext());
+            builder.setAdapter(mAdapter, null);
+            mAlertDialog = builder.create();
+            mAlertDialog.getListView().setOnItemClickListener(mCallbacks);
+            mAlertDialog.setOnDismissListener(mCallbacks);
+        }
+        return mAlertDialog;
+    }
+
+    /**
+     * Updates the buttons state.
+     */
+    private void updateButtons() {
+        final int activityCount = mAdapter.getActivityCount();
+        if (activityCount > 0) {
+            mDefaultActionButton.setVisibility(VISIBLE);
+            if (mAdapter.getCount() > 0) {
+                mExpandActivityOverflowButton.setEnabled(true);
+            } else {
+                mExpandActivityOverflowButton.setEnabled(false);
+            }
+            ResolveInfo activity = mAdapter.getDefaultActivity();
+            PackageManager packageManager = mContext.getPackageManager();
+            mDefaultActionButton.setBackgroundDrawable(activity.loadIcon(packageManager));
+        } else {
+            mDefaultActionButton.setVisibility(View.INVISIBLE);
+            mExpandActivityOverflowButton.setEnabled(false);
+        }
+    }
+
+    /**
+     * Interface implementation to avoid publishing them in the APIs.
+     */
+    private class Callbacks implements AdapterView.OnItemClickListener,
+            View.OnClickListener, View.OnLongClickListener, PopupWindow.OnDismissListener,
+            DialogInterface.OnDismissListener {
+
+        // AdapterView#OnItemClickListener
+        public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
+            ActivityChooserViewAdapter adapter = (ActivityChooserViewAdapter) parent.getAdapter();
+            final int itemViewType = adapter.getItemViewType(position);
+            switch (itemViewType) {
+                case ActivityChooserViewAdapter.ITEM_VIEW_TYPE_HEADER: {
+                    /* do nothing */
+                } break;
+                case ActivityChooserViewAdapter.ITEM_VIEW_TYPE_FOOTER: {
+                    showPopupUnchecked(ActivityChooserViewAdapter.MAX_ACTIVITY_COUNT_UNLIMITED);
+                } break;
+                case ActivityChooserViewAdapter.ITEM_VIEW_TYPE_ACTIVITY: {
+                    dismissPopup();
+                    if (mIsSelectingDefaultActivity) {
+                        mAdapter.getDataModel().setDefaultActivity(position);
+                    } else {
+                        // The first item in the model is default action => adjust index
+                        Intent launchIntent = mAdapter.getDataModel().chooseActivity(position + 1);
+                        mContext.startActivity(launchIntent);
+                    }
+                } break;
+                default:
+                    throw new IllegalArgumentException();
+            }
+        }
+
+        // View.OnClickListener
+        public void onClick(View view) {
+            if (view == mDefaultActionButton) {
+                dismissPopup();
+                ResolveInfo defaultActivity = mAdapter.getDefaultActivity();
+                final int index = mAdapter.getDataModel().getActivityIndex(defaultActivity);
+                Intent launchIntent = mAdapter.getDataModel().chooseActivity(index);
+                mContext.startActivity(launchIntent);
+            } else if (view == mExpandActivityOverflowButton) {
+                mIsSelectingDefaultActivity = false;
+                showPopupUnchecked(mInitialActivityCount);
+            } else {
+                throw new IllegalArgumentException();
+            }
+        }
+
+        // OnLongClickListener#onLongClick
+        @Override
+        public boolean onLongClick(View view) {
+            if (view == mDefaultActionButton) {
+                if (mAdapter.getCount() > 0) {
+                    mIsSelectingDefaultActivity = true;
+                    showPopupUnchecked(mInitialActivityCount);
+                }
+            } else {
+                throw new IllegalArgumentException();
+            }
+            return true;
+        }
+
+        // PopUpWindow.OnDismissListener#onDismiss
+        public void onDismiss() {
+            mIsShowingPopuWindow = false;
+            notifyOnDismissListener();
+        }
+
+        // DialogInterface.OnDismissListener#onDismiss
+        @Override
+        public void onDismiss(DialogInterface dialog) {
+            mIsShowingAlertDialog = false;
+            AlertDialog alertDialog = (AlertDialog) dialog;
+            alertDialog.setCustomTitle(null);
+            notifyOnDismissListener();
+        }
+
+        private void notifyOnDismissListener() {
+            if (mOnDismissListener != null) {
+                mOnDismissListener.onDismiss();
+            }
+        }
+    }
+
+    /**
+     * Adapter for backing the list of activities shown in the popup.
+     */
+    private class ActivityChooserViewAdapter extends BaseAdapter {
+
+        public static final int MAX_ACTIVITY_COUNT_UNLIMITED = Integer.MAX_VALUE;
+
+        public static final int MAX_ACTIVITY_COUNT_DEFAULT = 4;
+
+        private static final int ITEM_VIEW_TYPE_HEADER = 0;
+
+        private static final int ITEM_VIEW_TYPE_ACTIVITY = 1;
+
+        private static final int ITEM_VIEW_TYPE_FOOTER = 2;
+
+        private static final int ITEM_VIEW_TYPE_COUNT = 3;
+
+        private final DataSetObserver mDataSetOberver = new DataSetObserver() {
+
+            @Override
+            public void onChanged() {
+                super.onChanged();
+                notifyDataSetChanged();
+            }
+            @Override
+            public void onInvalidated() {
+                super.onInvalidated();
+                notifyDataSetInvalidated();
+            }
+        };
+
+        private ActivityChooserModel mDataModel;
+
+        private int mMaxActivityCount = MAX_ACTIVITY_COUNT_DEFAULT;
+
+        private ResolveInfo mDefaultActivity;
+
+        private View mHeaderView;
+
+        private View mFooterView;
+
+        public void setDataModel(ActivityChooserModel dataModel) {
+            mDataModel = dataModel;
+            mDataModel.registerObserver(mDataSetOberver);
+            notifyDataSetChanged();
+        }
+
+        @Override
+        public void notifyDataSetChanged() {
+            if (mDataModel.getActivityCount() > 0) {
+                mDefaultActivity = mDataModel.getDefaultActivity();
+            } else {
+                mDefaultActivity = null;
+            }
+            super.notifyDataSetChanged();
+        }
+
+        @Override
+        public int getItemViewType(int position) {
+            if (mHeaderView != null && position == 0) {
+                return ITEM_VIEW_TYPE_HEADER;
+            } else if (mFooterView != null && position == getCount() - 1) {
+                return ITEM_VIEW_TYPE_FOOTER;
+            } else {
+                return ITEM_VIEW_TYPE_ACTIVITY;
+            }
+        }
+
+        @Override
+        public int getViewTypeCount() {
+            return ITEM_VIEW_TYPE_COUNT;
+        }
+
+        public int getCount() {
+            int count = 0;
+            int activityCount = mDataModel.getActivityCount();
+            if (activityCount > 0) {
+                activityCount--;
+            }
+            count = Math.min(activityCount, mMaxActivityCount);
+            if (mHeaderView != null) {
+                count++;
+            }
+            if (mFooterView != null) {
+                count++;
+            }
+            return count;
+        }
+
+        public Object getItem(int position) {
+            final int itemViewType = getItemViewType(position);
+            switch (itemViewType) {
+                case ITEM_VIEW_TYPE_HEADER:
+                    return mHeaderView;
+                case ITEM_VIEW_TYPE_FOOTER:
+                    return mFooterView;
+                case ITEM_VIEW_TYPE_ACTIVITY:
+                    int targetIndex = (mHeaderView == null) ? position : position - 1;
+                    if (mDefaultActivity != null) {
+                        targetIndex++;
+                    }
+                    return mDataModel.getActivity(targetIndex);
+                default:
+                    throw new IllegalArgumentException();
+            }
+        }
+
+        public long getItemId(int position) {
+            return position;
+        }
+
+        @Override
+        public boolean isEnabled(int position) {
+            final int itemViewType = getItemViewType(position);
+            switch (itemViewType) {
+                case ITEM_VIEW_TYPE_HEADER:
+                    return false;
+                case ITEM_VIEW_TYPE_FOOTER:
+                case ITEM_VIEW_TYPE_ACTIVITY:
+                    return true;
+                default:
+                    throw new IllegalArgumentException();
+            }
+        }
+
+        public View getView(int position, View convertView, ViewGroup parent) {
+            final int itemViewType = getItemViewType(position);
+            switch (itemViewType) {
+                case ITEM_VIEW_TYPE_HEADER:
+                    return mHeaderView;
+                case ITEM_VIEW_TYPE_FOOTER:
+                    return mFooterView;
+                case ITEM_VIEW_TYPE_ACTIVITY:
+                    if (convertView == null || convertView.getId() != R.id.list_item) {
+                        convertView = LayoutInflater.from(getContext()).inflate(
+                                R.layout.activity_chooser_view_list_item, parent, false);
+                    }
+                    PackageManager packageManager = mContext.getPackageManager();
+                    // Set the icon
+                    ImageView iconView = (ImageView) convertView.findViewById(R.id.icon);
+                    ResolveInfo activity = (ResolveInfo) getItem(position);
+                    iconView.setBackgroundDrawable(activity.loadIcon(packageManager));
+                    // Set the title.
+                    TextView titleView = (TextView) convertView.findViewById(R.id.title);
+                    titleView.setText(activity.loadLabel(packageManager));
+                    return convertView;
+                default:
+                    throw new IllegalArgumentException();
+            }
+        }
+
+        public int measureContentWidth() {
+            // The user may have specified some of the target not to be show but we
+            // want to measure all of them since after expansion they should fit.
+            final int oldMaxActivityCount = mMaxActivityCount;
+            mMaxActivityCount = MAX_ACTIVITY_COUNT_UNLIMITED;
+
+            int contentWidth = 0;
+            View itemView = null;
+
+            final int widthMeasureSpec = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED);
+            final int heightMeasureSpec = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED);
+            final int count = getCount();
+
+            for (int i = 0; i < count; i++) {
+                itemView = getView(i, itemView, null);
+                itemView.measure(widthMeasureSpec, heightMeasureSpec);
+                contentWidth = Math.max(contentWidth, itemView.getMeasuredWidth());
+            }
+
+            mMaxActivityCount = oldMaxActivityCount;
+
+            return contentWidth;
+        }
+
+        public void setMaxActivityCount(int maxActivityCount) {
+            if (mMaxActivityCount != maxActivityCount) {
+                mMaxActivityCount = maxActivityCount;
+                notifyDataSetChanged();
+            }
+        }
+
+        public ResolveInfo getDefaultActivity() {
+            return mDefaultActivity;
+        }
+
+        public void setHeaderView(View headerView) {
+            if (mHeaderView != headerView) {
+                mHeaderView = headerView;
+                notifyDataSetChanged();
+            }
+        }
+
+        public void setFooterView(View footerView) {
+            if (mFooterView != footerView) {
+                mFooterView = footerView;
+                notifyDataSetChanged();
+            }
+        }
+
+        public int getActivityCount() {
+            return mDataModel.getActivityCount();
+        }
+
+        public int getMaxActivityCount() {
+            return mMaxActivityCount;
+        }
+
+        public ActivityChooserModel getDataModel() {
+            return mDataModel;
+        }
+    }
+}
diff --git a/core/java/android/widget/ShareActionProvider.java b/core/java/android/widget/ShareActionProvider.java
new file mode 100644
index 0000000..d6e426f
--- /dev/null
+++ b/core/java/android/widget/ShareActionProvider.java
@@ -0,0 +1,164 @@
+/*
+ * Copyright (C) 2011 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package android.widget;
+
+import android.content.Context;
+import android.content.Intent;
+import android.graphics.drawable.Drawable;
+import android.util.TypedValue;
+import android.view.ActionProvider;
+import android.view.MenuItem;
+import android.view.View;
+
+import com.android.internal.R;
+
+/**
+ * This is a provider for a share action. It is responsible for creating views
+ * that enable data sharing and also to perform a default action for showing
+ * a share dialog.
+ * <p>
+ * Here is how to use the action provider with custom backing file in a {@link MenuItem}:
+ * </p>
+ * <p>
+ * <pre>
+ * <code>
+ *  // In Activity#onCreateOptionsMenu
+ *  public boolean onCreateOptionsMenu(Menu menu) {
+ *      // Get the menu item.
+ *      MenuItem menuItem = menu.findItem(R.id.my_menu_item);
+ *      // Get the provider and hold onto it to set/change the share intent.
+ *      mShareActionProvider = (ShareActionProvider) menuItem.getActionProvider();
+ *      // Set history different from the default before getting the action
+ *      // view since a call to {@link MenuItem#getActionView() MenuItem.getActionView()} calls
+ *      // {@link ActionProvider#onCreateActionView()} which uses the backing file name. Omit this
+ *      // line if using the default share history file is desired.
+ *      mShareActionProvider.setShareHistoryFileName("custom_share_history.xml");
+ *      // Get the action view and hold onto it to set the share intent.
+ *      mActionView = menuItem.getActionView();
+ *      . . .
+ *  }
+ *
+ *  // Somewhere in the application.
+ *  public void doShare(Intent shareIntent) {
+ *      // When you want to share set the share intent.
+ *      mShareActionProvider.setShareIntent(mActionView, shareIntent);
+ *  }
+ * </pre>
+ * </code>
+ * </p>
+ * <p>
+ * <strong>Note:</strong> While the sample snippet demonstrates how to use this provider
+ * in the context of a menu item, the use of the provider is not limited to menu items.
+ * </p>
+ *
+ * @see ActionProvider
+ */
+public class ShareActionProvider extends ActionProvider {
+
+    /**
+     * The default name for storing share history.
+     */
+    public static final String DEFAULT_SHARE_HISTORY_FILE_NAME = "share_history.xml";
+
+    private final Context mContext;
+    private String mShareHistoryFileName = DEFAULT_SHARE_HISTORY_FILE_NAME;
+
+    /**
+     * Creates a new instance.
+     *
+     * @param context Context for accessing resources.
+     */
+    public ShareActionProvider(Context context) {
+        super(context);
+        mContext = context;
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    @Override
+    public View onCreateActionView() {
+        ActivityChooserModel dataModel = ActivityChooserModel.get(mContext, mShareHistoryFileName);
+        ActivityChooserView activityChooserView = new ActivityChooserView(mContext);
+        activityChooserView.setActivityChooserModel(dataModel);
+        TypedValue outTypedValue = new TypedValue();
+        mContext.getTheme().resolveAttribute(R.attr.actionModeShareDrawable, outTypedValue, true);
+        Drawable drawable = mContext.getResources().getDrawable(outTypedValue.resourceId);
+        activityChooserView.setExpandActivityOverflowButtonDrawable(drawable);
+        return activityChooserView;
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    @Override
+    public void onPerformDefaultAction(View actionView) {
+        if (actionView instanceof ActivityChooserView) {
+            ActivityChooserView activityChooserView = (ActivityChooserView) actionView;
+            activityChooserView.showPopup();
+        } else {
+            throw new IllegalArgumentException("actionView not instance of ActivityChooserView");
+        }
+    }
+
+    /**
+     * Sets the file name of a file for persisting the share history which
+     * history will be used for ordering share targets. This file will be used
+     * for all view created by {@link #onCreateActionView()}. Defaults to
+     * {@link #DEFAULT_SHARE_HISTORY_FILE_NAME}. Set to <code>null</code>
+     * if share history should not be persisted between sessions.
+     * <p>
+     * <strong>Note:</strong> The history file name can be set any time, however
+     * only the action views created by {@link #onCreateActionView()} after setting
+     * the file name will be backed by the provided file.
+     * <p>
+     *
+     * @param shareHistoryFile The share history file name.
+     */
+    public void setShareHistoryFileName(String shareHistoryFile) {
+        mShareHistoryFileName = shareHistoryFile;
+    }
+
+    /**
+     * Sets an intent with information about the share action. Here is a
+     * sample for constructing a share intent:
+     * <p>
+     * <pre>
+     * <code>
+     *  Intent shareIntent = new Intent(Intent.ACTION_SEND);
+     *  shareIntent.setType("image/*");
+     *  Uri uri = Uri.fromFile(new File(getFilesDir(), "foo.jpg"));
+     *  shareIntent.putExtra(Intent.EXTRA_STREAM, uri.toString());
+     * </pre>
+     * </code>
+     * </p>
+     *
+     * @param actionView An action view created by {@link #onCreateActionView()}.
+     * @param shareIntent The share intent.
+     *
+     * @see Intent#ACTION_SEND
+     * @see Intent#ACTION_SEND_MULTIPLE
+     */
+    public void setShareIntent(View actionView, Intent shareIntent) {
+        if (actionView instanceof ActivityChooserView) {
+            ActivityChooserView activityChooserView = (ActivityChooserView) actionView;
+            activityChooserView.getDataModel().setIntent(shareIntent);
+        } else {
+            throw new IllegalArgumentException("actionView not instance of ActivityChooserView");
+        }
+    }
+}
diff --git a/core/java/com/android/internal/view/menu/ActionMenuItem.java b/core/java/com/android/internal/view/menu/ActionMenuItem.java
index a4bcf60..2685046 100644
--- a/core/java/com/android/internal/view/menu/ActionMenuItem.java
+++ b/core/java/com/android/internal/view/menu/ActionMenuItem.java
@@ -19,6 +19,7 @@ package com.android.internal.view.menu;
 import android.content.Context;
 import android.content.Intent;
 import android.graphics.drawable.Drawable;
+import android.view.ActionProvider;
 import android.view.ContextMenu.ContextMenuInfo;
 import android.view.MenuItem;
 import android.view.SubMenu;
@@ -238,6 +239,16 @@ public class ActionMenuItem implements MenuItem {
     }
 
     @Override
+    public ActionProvider getActionProvider() {
+        return null;
+    }
+
+    @Override
+    public MenuItem setActionProvider(ActionProvider actionProvider) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
     public MenuItem setShowAsActionFlags(int actionEnum) {
         setShowAsAction(actionEnum);
         return this;
diff --git a/core/java/com/android/internal/view/menu/MenuItemImpl.java b/core/java/com/android/internal/view/menu/MenuItemImpl.java
index 253511c..7b1dfb0 100644
--- a/core/java/com/android/internal/view/menu/MenuItemImpl.java
+++ b/core/java/com/android/internal/view/menu/MenuItemImpl.java
@@ -23,6 +23,7 @@ import android.content.Context;
 import android.content.Intent;
 import android.graphics.drawable.Drawable;
 import android.util.Log;
+import android.view.ActionProvider;
 import android.view.ContextMenu.ContextMenuInfo;
 import android.view.LayoutInflater;
 import android.view.MenuItem;
@@ -79,6 +80,7 @@ public final class MenuItemImpl implements MenuItem {
     private int mShowAsAction = SHOW_AS_ACTION_NEVER;
 
     private View mActionView;
+    private ActionProvider mActionProvider;
     private OnActionExpandListener mOnActionExpandListener;
     private boolean mIsActionViewExpanded = false;
 
@@ -98,10 +100,8 @@ public final class MenuItemImpl implements MenuItem {
     
     
     /**
-     * Instantiates this menu item. The constructor
-     * {@link #MenuItemData(MenuBuilder, int, int, int, CharSequence, int)} is
-     * preferred due to lazy loading of the icon Drawable.
-     * 
+     * Instantiates this menu item.
+     *
      * @param menu
      * @param group Item ordering grouping control. The item will be added after
      *            all other items whose order is <= this number, and before any
@@ -154,7 +154,7 @@ public final class MenuItemImpl implements MenuItem {
             mItemCallback.run();
             return true;
         }
-        
+
         if (mIntent != null) {
             try {
                 mMenu.getContext().startActivity(mIntent);
@@ -163,7 +163,14 @@ public final class MenuItemImpl implements MenuItem {
                 Log.e(TAG, "Can't find activity to handle intent; ignoring", e);
             }
         }
-        
+
+        if (mActionProvider != null) {
+            // The action view is created by the provider in this case.
+            View actionView = getActionView();
+            mActionProvider.onPerformDefaultAction(actionView);
+            return true;
+        }
+
         return false;
     }
     
@@ -551,6 +558,7 @@ public final class MenuItemImpl implements MenuItem {
 
     public MenuItem setActionView(View view) {
         mActionView = view;
+        mActionProvider = null;
         mMenu.onItemActionRequestChanged(this);
         return this;
     }
@@ -563,7 +571,25 @@ public final class MenuItemImpl implements MenuItem {
     }
 
     public View getActionView() {
-        return mActionView;
+        if (mActionView != null) {
+            return mActionView;
+        } else if (mActionProvider != null) {
+            mActionView = mActionProvider.onCreateActionView();
+            return mActionView;
+        } else {
+            return null;
+        }
+    }
+
+    public ActionProvider getActionProvider() {
+        return mActionProvider;
+    }
+
+    public MenuItem setActionProvider(ActionProvider actionProvider) {
+        mActionView = null;
+        mActionProvider = actionProvider;
+        mMenu.onItemsChanged(false);
+        return this;
     }
 
     @Override
diff --git a/core/res/res/layout/activity_chooser_list_footer.xml b/core/res/res/layout/activity_chooser_list_footer.xml
new file mode 100644
index 0000000..7603a31
--- /dev/null
+++ b/core/res/res/layout/activity_chooser_list_footer.xml
@@ -0,0 +1,44 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- Copyright (C) 2011 The Android Open Source Project
+
+     Licensed under the Apache License, Version 2.0 (the "License");
+     you may not use this file except in compliance with the License.
+     You may obtain a copy of the License at
+
+          http://www.apache.org/licenses/LICENSE-2.0
+
+     Unless required by applicable law or agreed to in writing, software
+     distributed under the License is distributed on an "AS IS" BASIS,
+     WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+     See the License for the specific language governing permissions and
+     limitations under the License.
+-->
+
+<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    android:id="@+id/list_footer"
+    android:paddingLeft="16dip"
+    android:paddingRight="16dip"
+    android:layout_width="wrap_content"
+    android:layout_height="wrap_content"
+    android:gravity="center"
+    android:orientation="vertical">
+
+    <ImageView
+        android:id="@+id/divider"
+        android:layout_width="match_parent"
+        android:layout_height="2dip"
+        android:scaleType="fitXY"
+        android:gravity="fill_horizontal"
+        android:src="@drawable/divider_strong_holo" />
+
+    <TextView
+        android:id="@+id/title"
+        android:layout_width="wrap_content"
+        android:layout_height="48dip"
+        android:gravity="center"
+        android:textAppearance="?android:attr/textAppearanceLargePopupMenu"
+        android:duplicateParentState="true"
+        android:singleLine="true"
+        android:text="@string/activity_chooser_view_see_all" />
+
+</LinearLayout>
diff --git a/core/res/res/layout/activity_chooser_list_header.xml b/core/res/res/layout/activity_chooser_list_header.xml
new file mode 100644
index 0000000..867014b
--- /dev/null
+++ b/core/res/res/layout/activity_chooser_list_header.xml
@@ -0,0 +1,43 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- Copyright (C) 2011 The Android Open Source Project
+
+     Licensed under the Apache License, Version 2.0 (the "License");
+     you may not use this file except in compliance with the License.
+     You may obtain a copy of the License at
+
+          http://www.apache.org/licenses/LICENSE-2.0
+
+     Unless required by applicable law or agreed to in writing, software
+     distributed under the License is distributed on an "AS IS" BASIS,
+     WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+     See the License for the specific language governing permissions and
+     limitations under the License.
+-->
+
+<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    android:id="@+id/list_header"
+    android:paddingLeft="16dip"
+    android:paddingRight="16dip"
+    android:layout_width="wrap_content"
+    android:layout_height="wrap_content"
+    android:gravity="center"
+    android:orientation="vertical">
+
+    <TextView
+        android:id="@+id/title"
+        android:layout_width="wrap_content"
+        android:layout_height="?android:attr/dropdownListPreferredItemHeight"
+        android:gravity="center"
+        android:textAppearance="?android:attr/textAppearanceLargePopupMenu"
+        android:duplicateParentState="true"
+        android:singleLine="true" />
+
+    <ImageView
+        android:id="@+id/divider"
+        android:layout_width="match_parent"
+        android:layout_height="2dip"
+        android:scaleType="fitXY"
+        android:gravity="fill_horizontal"
+        android:src="@drawable/divider_strong_holo" />
+
+</LinearLayout>
diff --git a/core/res/res/layout/activity_chooser_view.xml b/core/res/res/layout/activity_chooser_view.xml
new file mode 100644
index 0000000..ccf49fc
--- /dev/null
+++ b/core/res/res/layout/activity_chooser_view.xml
@@ -0,0 +1,35 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+**
+** Copyright 2011, The Android Open Source Project
+**
+** Licensed under the Apache License, Version 2.0 (the "License");
+** you may not use this file except in compliance with the License.
+** You may obtain a copy of the License at
+**
+**     http://www.apache.org/licenses/LICENSE-2.0
+**
+** Unless required by applicable law or agreed to in writing, software
+** distributed under the License is distributed on an "AS IS" BASIS,
+** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+** See the License for the specific language governing permissions and
+** limitations under the License.
+*/
+-->
+<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    android:id="@+id/activity_chooser_view_content"
+    android:layout_width="wrap_content"
+    android:layout_height="wrap_content"
+    style="?android:attr/actionButtonStyle">
+
+    <ImageButton android:id="@+id/default_activity_button"
+        android:layout_width="32dip"
+        android:layout_height="32dip"
+        android:layout_marginLeft="16dip" />
+
+    <ImageButton android:id="@+id/expand_activities_button"
+        android:layout_width="32dip"
+        android:layout_height="32dip"
+        android:layout_marginLeft="16dip" />
+
+</LinearLayout>
diff --git a/core/res/res/layout/activity_chooser_view_list_item.xml b/core/res/res/layout/activity_chooser_view_list_item.xml
new file mode 100644
index 0000000..61b7e70
--- /dev/null
+++ b/core/res/res/layout/activity_chooser_view_list_item.xml
@@ -0,0 +1,43 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- Copyright (C) 2011 The Android Open Source Project
+
+     Licensed under the Apache License, Version 2.0 (the "License");
+     you may not use this file except in compliance with the License.
+     You may obtain a copy of the License at
+
+          http://www.apache.org/licenses/LICENSE-2.0
+
+     Unless required by applicable law or agreed to in writing, software
+     distributed under the License is distributed on an "AS IS" BASIS,
+     WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+     See the License for the specific language governing permissions and
+     limitations under the License.
+-->
+
+<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    android:id="@+id/list_item"
+    android:layout_width="match_parent"
+    android:layout_height="?android:attr/dropdownListPreferredItemHeight"
+    android:gravity="center_vertical"
+    android:paddingLeft="16dip"
+    android:paddingRight="16dip">
+
+    <ImageView
+        android:id="@+id/icon"
+        android:layout_width="32dip"
+        android:layout_height="32dip"
+        android:layout_gravity="center_vertical"
+        android:layout_marginRight="8dip"
+        android:duplicateParentState="true" />
+
+    <TextView
+        android:id="@+id/title"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:textAppearance="?android:attr/textAppearanceLargePopupMenu"
+        android:singleLine="true"
+        android:duplicateParentState="true"
+        android:ellipsize="marquee"
+        android:fadingEdge="horizontal" />
+
+</LinearLayout>
diff --git a/core/res/res/values/attrs.xml b/core/res/res/values/attrs.xml
index c84a591..aa8c510 100755
--- a/core/res/res/values/attrs.xml
+++ b/core/res/res/values/attrs.xml
@@ -4586,6 +4586,25 @@
              for more info. -->
         <attr name="actionViewClass" format="string" />
 
+        <!-- The name of an optional ActionProvider class to instantiate an action view
+             and perform operations such as default action for that menu item.
+             See {@link android.view.MenuItem#setActionProvider(android.view.ActionProvider)}
+             for more info. -->
+        <attr name="actionProviderClass" format="string" />
+
+    </declare-styleable>
+
+    <!-- Attrbitutes for a ActvityChooserView. -->
+    <declare-styleable name="ActivityChooserView">
+        <!-- The maximal number of items initially shown in the activity list. -->
+        <attr name="initialActivityCount" format="string" />
+        <!-- The drawable to show in the button for expanding the activities overflow popup.
+             <strong>Note:</strong> Clients would like to set this drawable
+             as a clue about the action the chosen activity will perform. For
+             example, if share activity is to be chosen the drawable should
+             give a clue that sharing is to be performed.
+         -->
+        <attr name="expandActivityOverflowButtonDrawable" format="reference" />
     </declare-styleable>
 
     <!-- **************************************************************** -->
diff --git a/core/res/res/values/public.xml b/core/res/res/values/public.xml
index 945e0c4..54e484e 100644
--- a/core/res/res/values/public.xml
+++ b/core/res/res/values/public.xml
@@ -1785,4 +1785,7 @@
   <public type="string" name="status_bar_notification_info_overflow" />
 
   <public type="attr" name="textDirection"/>
+
+  <public type="attr" name="actionProviderClass" />
+
 </resources>
diff --git a/core/res/res/values/strings.xml b/core/res/res/values/strings.xml
index c8b3b4f..c8599d0 100755
--- a/core/res/res/values/strings.xml
+++ b/core/res/res/values/strings.xml
@@ -3002,4 +3002,11 @@
     <!-- Label for an information field on an SSL Certificate Dialog -->
     <string name="expires_on">Expires on:</string>
 
+    <!-- Title for a button to expand the list of activities in ActivityChooserView [CHAR LIMIT=25] -->
+    <string name="activity_chooser_view_see_all">See all...</string>
+    <!-- Title for a message that there are no activities in ActivityChooserView [CHAR LIMIT=25] -->
+    <string name="activity_chooser_view_no_activities">No activities</string>
+    <!-- Title for a message that prompts selection of a default share handler in ActivityChooserView [CHAR LIMIT=25] -->
+    <string name="activity_chooser_view_select_default">Select default</string>
+
 </resources>