Homescreen migration from a larger grid to a smaller grid.

Adding support for restoring from a larger device, if the grid size
difference is not more that 1.
During restore add all the items in the DB, and run a one-time migration
the next time launcher starts.

The migration strategy is defined in ShrinkWorkspaceTask.java which involves
resizing, moving and removing some items.

Change-Id: I6ee411f6db5bf0152b527e16146a88c56dec2d97

src/com/android/launcher3/LauncherBackupAgentHelper.java

@@ -24,6 +24,8 @@ import android.database.Cursor;
 import android.os.ParcelFileDescriptor;
 import android.util.Log;
 
+import com.android.launcher3.model.MigrateFromRestoreTask;
+
 import java.io.IOException;
 
 public class LauncherBackupAgentHelper extends BackupAgentHelper {
@@ -96,6 +98,13 @@ public class LauncherBackupAgentHelper extends BackupAgentHelper {
                 LauncherAppState.getLauncherProvider().updateFolderItemsRank();
             }
 
+            if (mHelper.shouldAttemptWorkspaceMigration()) {
+                MigrateFromRestoreTask.markForMigration(getApplicationContext(),
+                        (int) mHelper.migrationCompatibleProfileData.desktopCols,
+                        (int) mHelper.migrationCompatibleProfileData.desktopRows,
+                        mHelper.widgetSizes);
+            }
+
             LauncherAppState.getLauncherProvider().convertShortcutsToLauncherActivities();
         } else {
             if (VERBOSE) Log.v(TAG, "Nothing was restored, clearing DB");