Add a service to handle postMessage callbacks to client

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

Index: customtabs/src/android/support/customtabs/ICustomTabsService.aidl
diff --git a/customtabs/src/android/support/customtabs/ICustomTabsService.aidl b/customtabs/src/android/support/customtabs/ICustomTabsService.aidl
index b0c601060bdf4a32b4d51ca62d9995c975f12578..b24b0ddf2e9b39b871e2aef466550c25f771a05a 100644
--- a/customtabs/src/android/support/customtabs/ICustomTabsService.aidl
+++ b/customtabs/src/android/support/customtabs/ICustomTabsService.aidl
@@ -16,6 +16,7 @@
 
 package android.support.customtabs;
 
+import android.content.ComponentName;
 import android.net.Uri;
 import android.os.Bundle;
 import android.support.customtabs.ICustomTabsCallback;
@@ -33,6 +34,6 @@ interface ICustomTabsService {
             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;
 }