- 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
ontents()->SetUserAgentOverride(
      blink::UserAgentOverride::UserAgentOnly(user_agent), false);
}
std::string WebContents::GetUserAgent() {
  return ontents()->GetUserAgentOverride().ua_string_override;
}
v8::Local<v8::Promise> WebContents::SavePage(
    const base::FilePath& full_file_path,
    const content::SavePageType& save_type) {
  v8::Isolate* isolate = JavascriptEnvironment::GetIsolate();
  gin_helper::Promise<void> promise(isolate);
  v8::Local<v8::Promise> handle = promise.GetHandle();
  auto* handler = new SavePageHandler(ontents(), std::move(promise));
  handler->Handle(full_file_path, save_type);
  return handle;
}
void WebContents::OpenDevTools(gin::Arguments* args) {