Add two-ways sync to Google Drive.

MyTracks/res/xml/sync_adapter.xml

@@ -0,0 +1,21 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+Copyright 2013 Google Inc.
+
+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.
+-->
+<sync-adapter xmlns:android="http://schemas.android.com/apk/res/android"
+        android:contentAuthority="com.google.android.maps.mytracks" 
+        android:accountType="com.google"
+        android:userVisible="true" 
+        android:supportsUploading="true" />