Resetting launcherProvider data if restore set was empty

Bug: 17332300
Change-Id: I6d2187cd1b1fa7a53e49b96eb109263f6b74b258
diff --git a/src/com/android/launcher3/LauncherBackupAgentHelper.java b/src/com/android/launcher3/LauncherBackupAgentHelper.java
index 7dd8cde..c20c693 100644
--- a/src/com/android/launcher3/LauncherBackupAgentHelper.java
+++ b/src/com/android/launcher3/LauncherBackupAgentHelper.java
@@ -17,13 +17,16 @@
 package com.android.launcher3;
 
 import android.app.backup.BackupAgentHelper;
+import android.app.backup.BackupDataInput;
 import android.app.backup.BackupManager;
-import android.app.backup.SharedPreferencesBackupHelper;
 import android.content.Context;
-import android.content.SharedPreferences;
+import android.database.Cursor;
+import android.os.ParcelFileDescriptor;
 import android.provider.Settings;
 import android.util.Log;
 
+import java.io.IOException;
+
 public class LauncherBackupAgentHelper extends BackupAgentHelper {
 
     private static final String TAG = "LauncherBackupAgentHelper";
@@ -54,7 +57,7 @@
         // modifies the file outside the normal codepaths, so it looks like another
         // process.  This forces a reload of the file, in case this process persists.
         String spKey = LauncherAppState.getSharedPreferencesKey();
-        SharedPreferences sp = getSharedPreferences(spKey, Context.MODE_MULTI_PROCESS);
+        getSharedPreferences(spKey, Context.MODE_MULTI_PROCESS);
         super.onDestroy();
     }
 
@@ -71,4 +74,21 @@
         addHelper(LauncherBackupHelper.LAUNCHER_PREFIX,
                 new LauncherBackupHelper(this, restoreEnabled));
     }
+
+    @Override
+    public void onRestore(BackupDataInput data, int appVersionCode, ParcelFileDescriptor newState)
+            throws IOException {
+        super.onRestore(data, appVersionCode, newState);
+
+        // If no favorite was migrated, clear the data and start fresh.
+        final Cursor c = getContentResolver().query(
+                LauncherSettings.Favorites.CONTENT_URI_NO_NOTIFICATION, null, null, null, null);
+        boolean hasData = c.moveToNext();
+        c.close();
+
+        if (!hasData) {
+            if (VERBOSE) Log.v(TAG, "Nothing was restored, clearing DB");
+            LauncherAppState.getLauncherProvider().createEmptyDB();
+        }
+    }
 }