- Electron version: 1.2.2
- Operating system: Linux

This is a problem only in linux. It works in OSX.

``` javascript
win.hide()
win.capturePage(function(img){
 // never called
})
```

shell/browser/api/electron_api_web_contents.cc
v8::Isolate* isolate,
      const scoped_refptr<content::DevToolsAgentHost>& val) {
    gin_helper::Dictionary dict(isolate, v8::Object::New(isolate));
    dict.Set("id", val->GetId());
    dict.Set("url", val->GetURL().spec());
    return dict.GetHandle();
  }
};
}  
namespace electron {
namespace api {
namespace {
base::IDMap<WebContents*>& GetAllWebContents() {