如何强制调用“onShowCustomView”方法（iframe）

Question

如何在Android 4上使用iframe播放“Youtube”视频时强制调用“onShowCustomView”方法。+

 mWebView.setWebChromeClient(new WebChromeClient(){
        public void onShowCustomView(View view, int requestedOrientation, WebChromeClient.CustomViewCallback callback){
            super.onShowCustomView(view, callback);   

        }
    });