Set the default backup transport.

overlay/frameworks/base/packages/SettingsProvider/res/values/defaults.xml

@@ -0,0 +1,21 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+/**
+ * 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.
+ */
+-->
+<resources>
+    <string name="def_backup_transport">com.google.android.backup/.BackupTransportService</string>
+</resources>