@Override
        public void onServiceConnected(ComponentName componentName, IBinder iBinder) {
            mService = new TrustedWebActivityServiceWrapper(
                    ITrustedWebActivityService.Stub.asInterface(iBinder), componentName);
            for (WrappedCallback callback : mCallbacks) {
                callback.onConnected(mService);
            }
            mCallbacks.clear();
        }
This method will be called on the UI Thread by the Android Framework.
customtabs/src/android/support/customtabs/trusted/TrustedWebActivityServiceConnectionManager.java