Start backing up wallpaper

This CL does the following:
   + adds an AbsoluteFileBackupHelper class for managing backup of files
     known by absolute path, not based off of the app's getFilesDir() root
   + bumps up the collection interval from its testing-only default of 1 second
     to 3 minutes
   + adds a SystemBackupAgent class to the main system package and names it as
     the android:backupAgent for the main OS package.  Right now this agent
     only backs up & restores the wallpaper file.
   + amend the Wallpaper Service to inform the Backup Manager when the wallpaper
     changes.

On the subject of the 3-minute collection interval before the backup actually
occurs:  this can be short-circuited from an adb shell.  Running the command
'bmgr run' will cause the Backup Manager to kick off any pending backup
operations immediately.

1 files changed, 66 insertions, 0 deletions

diff --git a/core/java/android/backup/AbsoluteFileBackupHelper.java b/core/java/android/backup/AbsoluteFileBackupHelper.java
new file mode 100644
index 0000000..ab24675
--- /dev/null
+++ b/core/java/android/backup/AbsoluteFileBackupHelper.java
@@ -0,0 +1,66 @@
+/*
+ * Copyright (C) 2009 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.backup;
+
+import android.content.Context;
+import android.os.ParcelFileDescriptor;
+import android.util.Log;
+
+import java.io.File;
+import java.io.FileDescriptor;
+
+/**
+ * Like FileBackupHelper, but takes absolute paths for the files instead of
+ * subpaths of getFilesDir()
+ *
+ * @hide
+ */
+public class AbsoluteFileBackupHelper extends FileBackupHelperBase implements BackupHelper {
+    private static final String TAG = "AbsoluteFileBackupHelper";
+
+    Context mContext;
+    String[] mFiles;
+
+    public AbsoluteFileBackupHelper(Context context, String... files) {
+        super(context);
+
+        mContext = context;
+        mFiles = files;
+    }
+
+    /**
+     * Based on oldState, determine which of the files from the application's data directory
+     * need to be backed up, write them to the data stream, and fill in newState with the
+     * state as it exists now.
+     */
+    public void performBackup(ParcelFileDescriptor oldState, BackupDataOutput data,
+            ParcelFileDescriptor newState) {
+        // use the file paths as the keys, too
+        performBackup_checked(oldState, data, newState, mFiles, mFiles);
+    }
+
+    public void restoreEntity(BackupDataInputStream data) {
+        // TODO: turn this off before ship
+        Log.d(TAG, "got entity '" + data.getKey() + "' size=" + data.size());
+        String key = data.getKey();
+        if (isKeyInList(key, mFiles)) {
+            File f = new File(key);
+            writeFile(f, data);
+        }
+    }
+}
+