@Override
        public boolean requestPostMessageChannelWithExtras(ICustomTabsCallback callback,
                                                 Uri postMessageOrigin, Bundle extras) {
            return CustomTabsService.this.requestPostMessageChannel(
                    new CustomTabsSessionToken(callback, getSessionIdFromBundle(extras)),
                    postMessageOrigin);
        }
File is a splash image to be shown on top of a Trusted Web Activity while the web contents
are loading.
customtabs/src/android/support/customtabs/CustomTabsService.java