manifest.json 中key值如何定义，从哪选定key值
js中this.loadingImg = "chrome-extension://pfohojdamlkbkkmnipjmnnapakmgfahk/img/loading1.gif"; pfohojdamlkbkkmnipjmnnapakmgfahk值从哪获得
http://blog.csdn.net/qq_27626333/article/details/51915019