Add a service to handle postMessage callbacks to client

customtabs/src/android/support/customtabs/ICustomTabsService.aidl

 /*
  * Copyright (C) 2015 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.support.customtabs;
 
+import android.content.ComponentName;
 import android.net.Uri;
 import android.os.Bundle;
 import android.support.customtabs.ICustomTabsCallback;
 
 import java.util.List;
 
 /**
  * Interface to a CustomTabsService.
  * @hide
  */
 interface ICustomTabsService {
     boolean warmup(long flags) = 1;
     boolean newSession(in ICustomTabsCallback callback) = 2;
     boolean mayLaunchUrl(in ICustomTabsCallback callback, in Uri url,
             in Bundle extras, in List<Bundle> otherLikelyBundles) = 3;
     Bundle extraCommand(String commandName, in Bundle args) = 4;
     boolean updateVisuals(in ICustomTabsCallback callback, in Bundle bundle) = 5;
-    boolean validatePostMessageOrigin(in ICustomTabsCallback callback) = 6;
+    boolean requestPostMessageChannel(in ICustomTabsCallback callback, in Uri postMessageOrigin) = 6;
     int postMessage(in ICustomTabsCallback callback, String message, in Bundle extras) = 7;
 }