Add a service to handle postMessage callbacks to client

customtabs/src/android/support/customtabs/PostMessageService.java

Index: customtabs/src/android/support/customtabs/PostMessageService.java
diff --git a/customtabs/src/android/support/customtabs/PostMessageService.java b/customtabs/src/android/support/customtabs/PostMessageService.java
new file mode 100644
index 0000000000000000000000000000000000000000..f4c288629096cb39153051b121247690c92079e7
--- /dev/null
+++ b/customtabs/src/android/support/customtabs/PostMessageService.java
@@ -0,0 +1,49 @@
+/*
+ * Copyright (C) 2017 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.app.Service;
+import android.content.Intent;
+import android.os.Bundle;
+import android.os.IBinder;
+import android.os.RemoteException;
+
+/**
+ * A service to receive postMessage related communication from a Custom Tabs provider.
+ */
+ public class PostMessageService extends Service {
+
+     private IPostMessageService.Stub mBinder = new IPostMessageService.Stub() {
+
+         @Override
+         public void onMessageChannelReady(
+                 ICustomTabsCallback callback, Bundle extras) throws RemoteException {
+             callback.onMessageChannelReady(extras);
+         }
+
+         @Override
+         public void onPostMessage(ICustomTabsCallback callback,
+                 String message, Bundle extras) throws RemoteException {
+             callback.onPostMessage(message, extras);
+         }
+     };
+
+     @Override
+     public IBinder onBind(Intent intent) {
+         return mBinder;
+     }
+ }