@Override
    final public IBinder onBind(Intent intent) {
        return mBinder;
    }
Returns the Android resource id of a drawable to be used for the small icon of the
notification. This is called by the provider as it is constructing the notification, so a
complete notification can be passed to the client.

Default behaviour looks for meta-data with the name {@link #SMALL_ICON_META_DATA_NAME} in
service section of the manifest.
@return A resource id for the small icon, or {@link #NO_ID} if not found.
customtabs/src/android/support/customtabs/trusted/TrustedWebActivityService.java