Merge "Initial changes to add callback on task stack changes. (Bug 17672056, Bug 18291345)" into lmp-mr1-dev

15 files changed, 191 insertions, 64 deletions

diff --git a/Android.mk b/Android.mk
index ce72a85..ab66bec 100644
--- a/Android.mk
+++ b/Android.mk
@@ -69,6 +69,7 @@ LOCAL_SRC_FILES += \
 	core/java/android/app/IActivityPendingResult.aidl \
 	core/java/android/app/IAlarmManager.aidl \
 	core/java/android/app/IAppTask.aidl \
+	core/java/android/app/ITaskStackListener.aidl \
 	core/java/android/app/IBackupAgent.aidl \
 	core/java/android/app/IInstrumentationWatcher.aidl \
 	core/java/android/app/INotificationManager.aidl \
diff --git a/core/java/android/app/ActivityManagerNative.java b/core/java/android/app/ActivityManagerNative.java
index 6ec48e5..06a26ec 100644
--- a/core/java/android/app/ActivityManagerNative.java
+++ b/core/java/android/app/ActivityManagerNative.java
@@ -774,6 +774,14 @@ public abstract class ActivityManagerNative extends Binder implements IActivityM
             return true;
         }
 
+        case REGISTER_TASK_STACK_LISTENER_TRANSACTION: {
+            data.enforceInterface(IActivityManager.descriptor);
+            IBinder token = data.readStrongBinder();
+            registerTaskStackListener(ITaskStackListener.Stub.asInterface(token));
+            reply.writeNoException();
+            return true;
+        }
+
         case GET_TASK_FOR_ACTIVITY_TRANSACTION: {
             data.enforceInterface(IActivityManager.descriptor);
             IBinder token = data.readStrongBinder();
@@ -3266,6 +3274,18 @@ class ActivityManagerProxy implements IActivityManager
         data.recycle();
         reply.recycle();
     }
+    @Override
+    public void registerTaskStackListener(ITaskStackListener listener) throws RemoteException
+    {
+        Parcel data = Parcel.obtain();
+        Parcel reply = Parcel.obtain();
+        data.writeInterfaceToken(IActivityManager.descriptor);
+        data.writeStrongBinder(listener.asBinder());
+        mRemote.transact(REGISTER_TASK_STACK_LISTENER_TRANSACTION, data, reply, IBinder.FLAG_ONEWAY);
+        reply.readException();
+        data.recycle();
+        reply.recycle();
+    }
     public int getTaskForActivity(IBinder token, boolean onlyRoot) throws RemoteException
     {
         Parcel data = Parcel.obtain();
diff --git a/core/java/android/app/IActivityManager.java b/core/java/android/app/IActivityManager.java
index 5362303..1ccbd27 100644
--- a/core/java/android/app/IActivityManager.java
+++ b/core/java/android/app/IActivityManager.java
@@ -139,6 +139,7 @@ public interface IActivityManager extends IInterface {
     public StackInfo getStackInfo(int stackId) throws RemoteException;
     public boolean isInHomeStack(int taskId) throws RemoteException;
     public void setFocusedStack(int stackId) throws RemoteException;
+    public void registerTaskStackListener(ITaskStackListener listener) throws RemoteException;
     public int getTaskForActivity(IBinder token, boolean onlyRoot) throws RemoteException;
     public ContentProviderHolder getContentProvider(IApplicationThread caller,
             String name, int userId, boolean stable) throws RemoteException;
@@ -788,4 +789,5 @@ public interface IActivityManager extends IInterface {
     int LAUNCH_ASSIST_INTENT_TRANSACTION = IBinder.FIRST_CALL_TRANSACTION+239;
     int START_IN_PLACE_ANIMATION_TRANSACTION = IBinder.FIRST_CALL_TRANSACTION+240;
     int CHECK_PERMISSION_WITH_TOKEN_TRANSACTION = IBinder.FIRST_CALL_TRANSACTION+241;
+    int REGISTER_TASK_STACK_LISTENER_TRANSACTION = IBinder.FIRST_CALL_TRANSACTION+242;
 }
diff --git a/core/java/android/app/ITaskStackListener.aidl b/core/java/android/app/ITaskStackListener.aidl
new file mode 100644
index 0000000..4b0935c
--- /dev/null
+++ b/core/java/android/app/ITaskStackListener.aidl
@@ -0,0 +1,22 @@
+/**
+ * Copyright (c) 2014, 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.app;
+
+/** @hide */
+oneway interface ITaskStackListener {
+    void onTaskStackChanged();
+}
diff --git a/packages/SystemUI/src/com/android/systemui/recents/AlternateRecentsComponent.java b/packages/SystemUI/src/com/android/systemui/recents/AlternateRecentsComponent.java
index 29f291d..4f0700e 100644
--- a/packages/SystemUI/src/com/android/systemui/recents/AlternateRecentsComponent.java
+++ b/packages/SystemUI/src/com/android/systemui/recents/AlternateRecentsComponent.java
@@ -19,6 +19,7 @@ package com.android.systemui.recents;
 import android.app.Activity;
 import android.app.ActivityManager;
 import android.app.ActivityOptions;
+import android.app.ITaskStackListener;
 import android.appwidget.AppWidgetHost;
 import android.appwidget.AppWidgetProviderInfo;
 import android.content.ActivityNotFoundException;
@@ -56,6 +57,7 @@ import java.util.ArrayList;
 import java.util.List;
 import java.util.concurrent.atomic.AtomicBoolean;
 
+
 /** A proxy implementation for the recents component */
 public class AlternateRecentsComponent implements ActivityOptions.OnAnimationStartedListener {
 
@@ -79,6 +81,28 @@ public class AlternateRecentsComponent implements ActivityOptions.OnAnimationSta
     final static String sRecentsPackage = "com.android.systemui";
     final static String sRecentsActivity = "com.android.systemui.recents.RecentsActivity";
 
+    /**
+     * An implementation of ITaskStackListener, that allows us to listen for changes to the system
+     * task stacks and update recents accordingly.
+     */
+    class TaskStackListenerImpl extends ITaskStackListener.Stub {
+        @Override
+        public void onTaskStackChanged() {
+            RecentsConfiguration config = RecentsConfiguration.getInstance();
+            if (config.svelteLevel == RecentsConfiguration.SVELTE_NONE) {
+                // Load the next task only if we aren't svelte
+                RecentsTaskLoader loader = RecentsTaskLoader.getInstance();
+                RecentsTaskLoadPlan plan = loader.createLoadPlan(mContext);
+                loader.preloadTasks(plan, true /* isTopTaskHome */);
+                RecentsTaskLoadPlan.Options launchOpts = new RecentsTaskLoadPlan.Options();
+                launchOpts.numVisibleTasks = 1;
+                launchOpts.numVisibleTaskThumbnails = 1;
+                launchOpts.onlyLoadForCache = true;
+                loader.loadTasks(mContext, plan, launchOpts);
+            }
+        }
+    }
+
     static RecentsComponent.Callbacks sRecentsComponentCallbacks;
     static RecentsTaskLoadPlan sInstanceLoadPlan;
 
@@ -86,6 +110,7 @@ public class AlternateRecentsComponent implements ActivityOptions.OnAnimationSta
     LayoutInflater mInflater;
     SystemServicesProxy mSystemServicesProxy;
     Handler mHandler;
+    TaskStackListenerImpl mTaskStackListener;
     boolean mBootCompleted;
     boolean mStartAnimationTriggered;
     boolean mCanReuseTaskStackViews = true;
@@ -116,6 +141,10 @@ public class AlternateRecentsComponent implements ActivityOptions.OnAnimationSta
         mSystemServicesProxy = new SystemServicesProxy(context);
         mHandler = new Handler();
         mTaskStackBounds = new Rect();
+
+        // Register the task stack listener
+        mTaskStackListener = new TaskStackListenerImpl();
+        mSystemServicesProxy.registerTaskStackListener(mTaskStackListener);
     }
 
     public void onStart() {
diff --git a/packages/SystemUI/src/com/android/systemui/recents/RecentsActivity.java b/packages/SystemUI/src/com/android/systemui/recents/RecentsActivity.java
index 6dc2edb..a37bc54 100644
--- a/packages/SystemUI/src/com/android/systemui/recents/RecentsActivity.java
+++ b/packages/SystemUI/src/com/android/systemui/recents/RecentsActivity.java
@@ -167,10 +167,6 @@ public class RecentsActivity extends Activity implements RecentsView.RecentsView
             if (action.equals(Intent.ACTION_SCREEN_OFF)) {
                 // When the screen turns off, dismiss Recents to Home
                 dismissRecentsToHome(false);
-                // Preload the metadata for all tasks in the background
-                RecentsTaskLoader loader = RecentsTaskLoader.getInstance();
-                RecentsTaskLoadPlan plan = loader.createLoadPlan(context);
-                loader.preloadTasks(plan, true /* isTopTaskHome */);
             } else if (action.equals(SearchManager.INTENT_GLOBAL_SEARCH_ACTIVITY_CHANGED)) {
                 // When the search activity changes, update the Search widget
                 refreshSearchWidget();
@@ -437,22 +433,6 @@ public class RecentsActivity extends Activity implements RecentsView.RecentsView
             onEnterAnimationTriggered();
         }
 
-        // Start listening for widget package changes if there is one bound, post it since we don't
-        // want it stalling the startup
-        if (mConfig.searchBarAppWidgetId >= 0) {
-            final WeakReference<RecentsAppWidgetHost.RecentsAppWidgetHostCallbacks> callback =
-                    new WeakReference<RecentsAppWidgetHost.RecentsAppWidgetHostCallbacks>(this);
-            mRecentsView.post(new Runnable() {
-                @Override
-                public void run() {
-                    RecentsAppWidgetHost.RecentsAppWidgetHostCallbacks cb = callback.get();
-                    if (cb != null) {
-                        mAppWidgetHost.startListening(cb);
-                    }
-                }
-            });
-        }
-
         mStatusBar = ((SystemUIApplication) getApplication())
                 .getComponent(PhoneStatusBar.class);
     }
@@ -539,15 +519,29 @@ public class RecentsActivity extends Activity implements RecentsView.RecentsView
         unregisterReceiver(mSystemBroadcastReceiver);
 
         // Stop listening for widget package changes if there was one bound
-        if (mAppWidgetHost.isListening()) {
-            mAppWidgetHost.stopListening();
-        }
+        mAppWidgetHost.stopListening();
     }
 
     public void onEnterAnimationTriggered() {
         // Try and start the enter animation (or restart it on configuration changed)
         ReferenceCountedTrigger t = new ReferenceCountedTrigger(this, null, null, null);
-        mRecentsView.startEnterRecentsAnimation(new ViewAnimation.TaskViewEnterContext(t));
+        ViewAnimation.TaskViewEnterContext ctx = new ViewAnimation.TaskViewEnterContext(t);
+        mRecentsView.startEnterRecentsAnimation(ctx);
+        if (mConfig.searchBarAppWidgetId >= 0) {
+            final WeakReference<RecentsAppWidgetHost.RecentsAppWidgetHostCallbacks> cbRef =
+                    new WeakReference<RecentsAppWidgetHost.RecentsAppWidgetHostCallbacks>(
+                            RecentsActivity.this);
+            ctx.postAnimationTrigger.addLastDecrementRunnable(new Runnable() {
+                @Override
+                public void run() {
+                    // Start listening for widget package changes if there is one bound
+                    RecentsAppWidgetHost.RecentsAppWidgetHostCallbacks cb = cbRef.get();
+                    if (cb != null) {
+                        mAppWidgetHost.startListening(cb);
+                    }
+                }
+            });
+        }
 
         // Animate the SystemUI scrim views
         mScrimViews.startEnterRecentsAnimation();
diff --git a/packages/SystemUI/src/com/android/systemui/recents/RecentsAppWidgetHost.java b/packages/SystemUI/src/com/android/systemui/recents/RecentsAppWidgetHost.java
index a63e167..5bae37a 100644
--- a/packages/SystemUI/src/com/android/systemui/recents/RecentsAppWidgetHost.java
+++ b/packages/SystemUI/src/com/android/systemui/recents/RecentsAppWidgetHost.java
@@ -43,23 +43,23 @@ public class RecentsAppWidgetHost extends AppWidgetHost {
 
     public void startListening(RecentsAppWidgetHostCallbacks cb) {
         mCb = cb;
-        mIsListening = true;
-        super.startListening();
+        if (!mIsListening) {
+            mIsListening = true;
+            super.startListening();
+        }
     }
 
     @Override
     public void stopListening() {
-        super.stopListening();
+        if (mIsListening) {
+            super.stopListening();
+        }
         // Ensure that we release any references to the callbacks
         mCb = null;
         mContext = null;
         mIsListening = false;
     }
 
-    public boolean isListening() {
-        return mIsListening;
-    }
-
     @Override
     protected void onProviderChanged(int appWidgetId, AppWidgetProviderInfo appWidgetInfo) {
         if (mCb == null) return;
diff --git a/packages/SystemUI/src/com/android/systemui/recents/misc/SystemServicesProxy.java b/packages/SystemUI/src/com/android/systemui/recents/misc/SystemServicesProxy.java
index 9a4bd08..3fbd5a6 100644
--- a/packages/SystemUI/src/com/android/systemui/recents/misc/SystemServicesProxy.java
+++ b/packages/SystemUI/src/com/android/systemui/recents/misc/SystemServicesProxy.java
@@ -21,6 +21,7 @@ import android.app.ActivityManagerNative;
 import android.app.ActivityOptions;
 import android.app.AppGlobals;
 import android.app.IActivityManager;
+import android.app.ITaskStackListener;
 import android.app.SearchManager;
 import android.appwidget.AppWidgetHost;
 import android.appwidget.AppWidgetManager;
@@ -536,4 +537,15 @@ public class SystemServicesProxy {
             e.printStackTrace();
         }
     }
+
+    /** Registers a task stack listener with the system. */
+    public void registerTaskStackListener(ITaskStackListener listener) {
+        if (mIam == null) return;
+
+        try {
+            mIam.registerTaskStackListener(listener);
+        } catch (Exception e) {
+            e.printStackTrace();
+        }
+    }
 }
diff --git a/packages/SystemUI/src/com/android/systemui/recents/views/RecentsView.java b/packages/SystemUI/src/com/android/systemui/recents/views/RecentsView.java
index 46a5d8d..746a7df 100644
--- a/packages/SystemUI/src/com/android/systemui/recents/views/RecentsView.java
+++ b/packages/SystemUI/src/com/android/systemui/recents/views/RecentsView.java
@@ -204,6 +204,10 @@ public class RecentsView extends FrameLayout implements TaskStackView.TaskStackV
 
     /** Requests all task stacks to start their enter-recents animation */
     public void startEnterRecentsAnimation(ViewAnimation.TaskViewEnterContext ctx) {
+        // We have to increment/decrement the post animation trigger in case there are no children
+        // to ensure that it runs
+        ctx.postAnimationTrigger.increment();
+
         int childCount = getChildCount();
         for (int i = 0; i < childCount; i++) {
             View child = getChildAt(i);
@@ -212,6 +216,7 @@ public class RecentsView extends FrameLayout implements TaskStackView.TaskStackV
                 stackView.startEnterRecentsAnimation(ctx);
             }
         }
+        ctx.postAnimationTrigger.decrement();
     }
 
     /** Requests all task stacks to start their exit-recents animation */
diff --git a/packages/SystemUI/src/com/android/systemui/recents/views/ViewAnimation.java b/packages/SystemUI/src/com/android/systemui/recents/views/ViewAnimation.java
index 4586f12..e1d80fd 100644
--- a/packages/SystemUI/src/com/android/systemui/recents/views/ViewAnimation.java
+++ b/packages/SystemUI/src/com/android/systemui/recents/views/ViewAnimation.java
@@ -27,7 +27,7 @@ public class ViewAnimation {
     public static class TaskViewEnterContext {
         // A trigger to run some logic when all the animations complete.  This works around the fact
         // that it is difficult to coordinate ViewPropertyAnimators
-        ReferenceCountedTrigger postAnimationTrigger;
+        public ReferenceCountedTrigger postAnimationTrigger;
         // An update listener to notify as the enter animation progresses (used for the home transition)
         ValueAnimator.AnimatorUpdateListener updateListener;
 
diff --git a/services/core/java/com/android/server/am/ActivityManagerService.java b/services/core/java/com/android/server/am/ActivityManagerService.java
index 7e17043..6823119 100755
--- a/services/core/java/com/android/server/am/ActivityManagerService.java
+++ b/services/core/java/com/android/server/am/ActivityManagerService.java
@@ -37,6 +37,7 @@ import android.app.ApplicationThreadNative;
 import android.app.IActivityContainer;
 import android.app.IActivityContainerCallback;
 import android.app.IAppTask;
+import android.app.ITaskStackListener;
 import android.app.ProfilerInfo;
 import android.app.admin.DevicePolicyManager;
 import android.app.usage.UsageEvents;
@@ -292,7 +293,7 @@ public final class ActivityManagerService extends ActivityManagerNative
     static final boolean IS_USER_BUILD = "user".equals(Build.TYPE);
 
     // Maximum number recent bitmaps to keep in memory.
-    static final int MAX_RECENT_BITMAPS = 5;
+    static final int MAX_RECENT_BITMAPS = 3;
 
     // Amount of time after a call to stopAppSwitches() during which we will
     // prevent further untrusted switches from happening.
@@ -370,6 +371,9 @@ public final class ActivityManagerService extends ActivityManagerNative
 
     static final int LAST_PREBOOT_DELIVERED_FILE_VERSION = 10000;
 
+    // Delay in notifying task stack change listeners (in millis)
+    static final int NOTIFY_TASK_STACK_CHANGE_LISTENERS_DELAY = 1000;
+
     /** All system services */
     SystemServiceManager mSystemServiceManager;
 
@@ -378,6 +382,10 @@ public final class ActivityManagerService extends ActivityManagerNative
     /** Run all ActivityStacks through this */
     ActivityStackSupervisor mStackSupervisor;
 
+    /** Task stack change listeners. */
+    private RemoteCallbackList<ITaskStackListener> mTaskStackListeners =
+            new RemoteCallbackList<ITaskStackListener>();
+
     public IntentFirewall mIntentFirewall;
 
     // Whether we should show our dialogs (ANR, crash, etc) or just perform their
@@ -1219,6 +1227,7 @@ public final class ActivityManagerService extends ActivityManagerNative
     static final int START_USER_SWITCH_MSG = 46;
     static final int SEND_LOCALE_TO_MOUNT_DAEMON_MSG = 47;
     static final int DISMISS_DIALOG_MSG = 48;
+    static final int NOTIFY_TASK_STACK_CHANGE_LISTENERS_MSG = 49;
 
     static final int FIRST_ACTIVITY_STACK_MSG = 100;
     static final int FIRST_BROADCAST_QUEUE_MSG = 200;
@@ -1738,6 +1747,22 @@ public final class ActivityManagerService extends ActivityManagerNative
                 d.dismiss();
                 break;
             }
+            case NOTIFY_TASK_STACK_CHANGE_LISTENERS_MSG: {
+                synchronized (ActivityManagerService.this) {
+                    int i = mTaskStackListeners.beginBroadcast();
+                    while (i > 0) {
+                        i--;
+                        try {
+                            // Make a one-way callback to the listener
+                            mTaskStackListeners.getBroadcastItem(i).onTaskStackChanged();
+                        } catch (RemoteException e){
+                            // Handled by the RemoteCallbackList
+                        }
+                    }
+                    mTaskStackListeners.finishBroadcast();
+                }
+                break;
+            }
             }
         }
     };
@@ -2332,6 +2357,16 @@ public final class ActivityManagerService extends ActivityManagerNative
         }
     }
 
+    /** Sets the task stack listener that gets callbacks when a task stack changes. */
+    @Override
+    public void registerTaskStackListener(ITaskStackListener listener) throws RemoteException {
+        synchronized (ActivityManagerService.this) {
+            if (listener != null) {
+                mTaskStackListeners.register(listener);
+            }
+        }
+    }
+
     @Override
     public void notifyActivityDrawn(IBinder token) {
         if (DEBUG_VISBILITY) Slog.d(TAG, "notifyActivityDrawn: token=" + token);
@@ -3643,12 +3678,12 @@ public final class ActivityManagerService extends ActivityManagerNative
                 if(DEBUG_TASKS) Slog.i(TAG, "remove RecentTask " + tr
                         + " when finishing user" + userId);
                 mRecentTasks.remove(i);
-                tr.removedFromRecents(mTaskPersister);
+                tr.removedFromRecents();
             }
         }
 
         // Remove tasks from persistent storage.
-        mTaskPersister.wakeup(null, true);
+        notifyTaskPersisterLocked(null, true);
     }
 
     // Sort by taskId
@@ -3660,7 +3695,7 @@ public final class ActivityManagerService extends ActivityManagerNative
     };
 
     // Extract the affiliates of the chain containing mRecentTasks[start].
-    private int processNextAffiliateChain(int start) {
+    private int processNextAffiliateChainLocked(int start) {
         final TaskRecord startTask = mRecentTasks.get(start);
         final int affiliateId = startTask.mAffiliatedTaskId;
 
@@ -3695,7 +3730,7 @@ public final class ActivityManagerService extends ActivityManagerNative
         if (first.mNextAffiliate != null) {
             Slog.w(TAG, "Link error 1 first.next=" + first.mNextAffiliate);
             first.setNextAffiliate(null);
-            mTaskPersister.wakeup(first, false);
+            notifyTaskPersisterLocked(first, false);
         }
         // Everything in the middle is doubly linked from next to prev.
         final int tmpSize = mTmpRecents.size();
@@ -3706,13 +3741,13 @@ public final class ActivityManagerService extends ActivityManagerNative
                 Slog.w(TAG, "Link error 2 next=" + next + " prev=" + next.mPrevAffiliate +
                         " setting prev=" + prev);
                 next.setPrevAffiliate(prev);
-                mTaskPersister.wakeup(next, false);
+                notifyTaskPersisterLocked(next, false);
             }
             if (prev.mNextAffiliate != next) {
                 Slog.w(TAG, "Link error 3 prev=" + prev + " next=" + prev.mNextAffiliate +
                         " setting next=" + next);
                 prev.setNextAffiliate(next);
-                mTaskPersister.wakeup(prev, false);
+                notifyTaskPersisterLocked(prev, false);
             }
             prev.inRecents = true;
         }
@@ -3721,7 +3756,7 @@ public final class ActivityManagerService extends ActivityManagerNative
         if (last.mPrevAffiliate != null) {
             Slog.w(TAG, "Link error 4 last.prev=" + last.mPrevAffiliate);
             last.setPrevAffiliate(null);
-            mTaskPersister.wakeup(last, false);
+            notifyTaskPersisterLocked(last, false);
         }
 
         // Insert the group back into mRecentTasks at start.
@@ -3762,7 +3797,7 @@ public final class ActivityManagerService extends ActivityManagerNative
                 if (task.autoRemoveRecents && task.getTopActivity() == null) {
                     // This situation is broken, and we should just get rid of it now.
                     mRecentTasks.remove(i);
-                    task.removedFromRecents(mTaskPersister);
+                    task.removedFromRecents();
                     i--;
                     N--;
                     Slog.w(TAG, "Removing auto-remove without activity: " + task);
@@ -3807,7 +3842,7 @@ public final class ActivityManagerService extends ActivityManagerNative
                         if (app == dummyApp || (app.flags&ApplicationInfo.FLAG_INSTALLED) == 0) {
                             // Doesn't exist any more!  Good-bye.
                             mRecentTasks.remove(i);
-                            task.removedFromRecents(mTaskPersister);
+                            task.removedFromRecents();
                             i--;
                             N--;
                             Slog.w(TAG, "Removing no longer valid recent: " + task);
@@ -3843,7 +3878,7 @@ public final class ActivityManagerService extends ActivityManagerNative
         }
 
         // Verify the affiliate chain for each task.
-        for (int i = 0; i < N; i = processNextAffiliateChain(i)) {
+        for (int i = 0; i < N; i = processNextAffiliateChainLocked(i)) {
         }
 
         mTmpRecents.clear();
@@ -4009,12 +4044,12 @@ public final class ActivityManagerService extends ActivityManagerNative
         }
 
         if (DEBUG_RECENTS) Slog.d(TAG, "addRecent: trimming tasks for " + task);
-        trimRecentsForTask(task, true);
+        trimRecentsForTaskLocked(task, true);
 
         N = mRecentTasks.size();
         while (N >= ActivityManager.getMaxRecentTasksStatic()) {
             final TaskRecord tr = mRecentTasks.remove(N - 1);
-            tr.removedFromRecents(mTaskPersister);
+            tr.removedFromRecents();
             N--;
         }
         task.inRecents = true;
@@ -4079,7 +4114,7 @@ public final class ActivityManagerService extends ActivityManagerNative
      * If needed, remove oldest existing entries in recents that are for the same kind
      * of task as the given one.
      */
-    int trimRecentsForTask(TaskRecord task, boolean doTrim) {
+    int trimRecentsForTaskLocked(TaskRecord task, boolean doTrim) {
         int N = mRecentTasks.size();
         final Intent intent = task.intent;
         final boolean document = intent != null && intent.isDocument();
@@ -4126,7 +4161,7 @@ public final class ActivityManagerService extends ActivityManagerNative
             tr.disposeThumbnail();
             mRecentTasks.remove(i);
             if (task != tr) {
-                tr.removedFromRecents(mTaskPersister);
+                tr.removedFromRecents();
             }
             i--;
             N--;
@@ -7989,10 +8024,6 @@ public final class ActivityManagerService extends ActivityManagerNative
         return list;
     }
 
-    TaskRecord getMostRecentTask() {
-        return mRecentTasks.get(0);
-    }
-
     /**
      * Creates a new RecentTaskInfo from a TaskRecord.
      */
@@ -8221,7 +8252,7 @@ public final class ActivityManagerService extends ActivityManagerNative
                 TaskRecord task = new TaskRecord(this, mStackSupervisor.getNextTaskId(), ainfo,
                         intent, description);
 
-                int trimIdx = trimRecentsForTask(task, false);
+                int trimIdx = trimRecentsForTaskLocked(task, false);
                 if (trimIdx >= 0) {
                     // If this would have caused a trim, then we'll abort because that
                     // means it would be added at the end of the list but then just removed.
@@ -8231,7 +8262,7 @@ public final class ActivityManagerService extends ActivityManagerNative
                 final int N = mRecentTasks.size();
                 if (N >= (ActivityManager.getMaxRecentTasksStatic()-1)) {
                     final TaskRecord tr = mRecentTasks.remove(N - 1);
-                    tr.removedFromRecents(mTaskPersister);
+                    tr.removedFromRecents();
                 }
 
                 task.inRecents = true;
@@ -8291,7 +8322,7 @@ public final class ActivityManagerService extends ActivityManagerNative
 
     private void cleanUpRemovedTaskLocked(TaskRecord tr, boolean killProcess) {
         mRecentTasks.remove(tr);
-        tr.removedFromRecents(mTaskPersister);
+        tr.removedFromRecents();
         ComponentName component = tr.getBaseIntent().getComponent();
         if (component == null) {
             Slog.w(TAG, "No component for base intent of task: " + tr);
@@ -9979,6 +10010,7 @@ public final class ActivityManagerService extends ActivityManagerNative
         }
     }
 
+    /** Pokes the task persister. */
     void notifyTaskPersisterLocked(TaskRecord task, boolean flush) {
         if (task != null && task.stack != null && task.stack.isHomeStack()) {
             // Never persist the home stack.
@@ -9987,6 +10019,13 @@ public final class ActivityManagerService extends ActivityManagerNative
         mTaskPersister.wakeup(task, flush);
     }
 
+    /** Notifies all listeners when the task stack has changed. */
+    void notifyTaskStackChangedLocked() {
+        mHandler.removeMessages(NOTIFY_TASK_STACK_CHANGE_LISTENERS_MSG);
+        Message nmsg = mHandler.obtainMessage(NOTIFY_TASK_STACK_CHANGE_LISTENERS_MSG);
+        mHandler.sendMessageDelayed(nmsg, NOTIFY_TASK_STACK_CHANGE_LISTENERS_DELAY);
+    }
+
     @Override
     public boolean shutdown(int timeout) {
         if (checkCallingPermission(android.Manifest.permission.SHUTDOWN)
@@ -10010,12 +10049,12 @@ public final class ActivityManagerService extends ActivityManagerNative
         mBatteryStatsService.shutdown();
         synchronized (this) {
             mProcessStats.shutdownLocked();
+            notifyTaskPersisterLocked(null, true);
         }
-        notifyTaskPersisterLocked(null, true);
 
         return timedout;
     }
-    
+
     public final void activitySlept(IBinder token) {
         if (localLOGV) Slog.v(TAG, "Activity slept: token=" + token);
 
diff --git a/services/core/java/com/android/server/am/ActivityRecord.java b/services/core/java/com/android/server/am/ActivityRecord.java
index c12cadb..e37d5f3 100755
--- a/services/core/java/com/android/server/am/ActivityRecord.java
+++ b/services/core/java/com/android/server/am/ActivityRecord.java
@@ -69,7 +69,7 @@ import java.util.Objects;
 final class ActivityRecord {
     static final String TAG = ActivityManagerService.TAG;
     static final boolean DEBUG_SAVED_STATE = ActivityStackSupervisor.DEBUG_SAVED_STATE;
-    final public static String RECENTS_PACKAGE_NAME = "com.android.systemui.recent";
+    final public static String RECENTS_PACKAGE_NAME = "com.android.systemui.recents";
 
     private static final String TAG_ACTIVITY = "activity";
     private static final String ATTR_ID = "id";
@@ -792,7 +792,7 @@ final class ActivityRecord {
         }
     }
 
-    void updateThumbnail(Bitmap newThumbnail, CharSequence description) {
+    void updateThumbnailLocked(Bitmap newThumbnail, CharSequence description) {
         if (newThumbnail != null) {
             if (ActivityManagerService.DEBUG_THUMBNAILS) Slog.i(ActivityManagerService.TAG,
                     "Setting thumbnail of " + this + " to " + newThumbnail);
diff --git a/services/core/java/com/android/server/am/ActivityStack.java b/services/core/java/com/android/server/am/ActivityStack.java
index ea694ad..ad86aea 100755
--- a/services/core/java/com/android/server/am/ActivityStack.java
+++ b/services/core/java/com/android/server/am/ActivityStack.java
@@ -65,7 +65,6 @@ import android.content.Intent;
 import android.content.pm.ActivityInfo;
 import android.content.pm.PackageManager;
 import android.content.res.Configuration;
-import android.content.res.Resources;
 import android.graphics.Bitmap;
 import android.net.Uri;
 import android.os.Binder;
@@ -838,7 +837,7 @@ final class ActivityStack {
         clearLaunchTime(prev);
         final ActivityRecord next = mStackSupervisor.topRunningActivityLocked();
         if (mService.mHasRecents && (next == null || next.noDisplay || next.task != prev.task || uiSleeping)) {
-            prev.updateThumbnail(screenshotActivities(prev), null);
+            prev.updateThumbnailLocked(screenshotActivities(prev), null);
         }
         stopFullyDrawnTraceIfNeeded();
 
@@ -950,7 +949,7 @@ final class ActivityStack {
             r.icicle = icicle;
             r.haveState = true;
             r.launchCount = 0;
-            r.updateThumbnail(null, description);
+            r.updateThumbnailLocked(null, description);
         }
         if (!r.stopped) {
             if (DEBUG_STATES) Slog.v(TAG, "Moving to STOPPED: " + r + " (stop complete)");
@@ -1060,6 +1059,9 @@ final class ActivityStack {
             }
             prev.cpuTimeAtResume = 0; // reset it
         }
+
+        // Notfiy when the task stack has changed
+        mService.notifyTaskStackChangedLocked();
     }
 
     /**
@@ -4105,7 +4107,7 @@ final class ActivityStack {
                 // Task creator asked to remove this when done, or this task was a voice
                 // interaction, so it should not remain on the recent tasks list.
                 mService.mRecentTasks.remove(task);
-                task.removedFromRecents(mService.mTaskPersister);
+                task.removedFromRecents();
             }
         }
 
diff --git a/services/core/java/com/android/server/am/ActivityStackSupervisor.java b/services/core/java/com/android/server/am/ActivityStackSupervisor.java
index 38809cb..d9396d8 100644
--- a/services/core/java/com/android/server/am/ActivityStackSupervisor.java
+++ b/services/core/java/com/android/server/am/ActivityStackSupervisor.java
@@ -2871,6 +2871,7 @@ public final class ActivityStackSupervisor implements DisplayListener {
         final TaskRecord task = r.task;
         task.setLastThumbnail(task.stack.screenshotActivities(r));
         mService.addRecentTaskLocked(task);
+        mService.notifyTaskStackChangedLocked();
         mWindowManager.setAppVisibility(r.appToken, false);
     }
 
diff --git a/services/core/java/com/android/server/am/TaskRecord.java b/services/core/java/com/android/server/am/TaskRecord.java
index ee93233..d726685 100644
--- a/services/core/java/com/android/server/am/TaskRecord.java
+++ b/services/core/java/com/android/server/am/TaskRecord.java
@@ -383,12 +383,12 @@ final class TaskRecord {
         setNextAffiliate(null);
     }
 
-    void removedFromRecents(TaskPersister persister) {
+    void removedFromRecents() {
         disposeThumbnail();
         closeRecentsChain();
         if (inRecents) {
             inRecents = false;
-            persister.wakeup(this, false);
+            mService.notifyTaskPersisterLocked(this, false);
         }
     }