Steps to reproduce the problem:
Load a remote DevTools front-end in a webview (same Electron version on both ends)

What is the expected behavior?
Remote DevTools is opened in the webview

What went wrong?
"Uncaught TypeError: Cannot read property 'extensions' of undefined".
At this point, it tries to access window.runtime.extensions("settings").
See screenshot.

Did this work before? Yes 51.0.2704.63

Chrome version: 52.0.2743.82
OS Version: OS X 10.11.4

Worked fine until Electron 1.2.0 (Chromium 51.0.2704.63) with the disablewebsecurity attribute set. Broken on 1.2.1.
Current chromium version (1.3.0): 52.0.2743.82

![screen shot 2016-07-25 at 5 36 13 pm](https://cloud.githubusercontent.com/assets/1028286/17125639/1a265cce-52aa-11e6-8413-2d75c642dbb2.png)

atom/common/node_bindings.cc
node::LoadEnvironment(env);
  mate::EmitEvent(env->isolate(), env->process_object(), "loaded");
}
void NodeBindings::PrepareMessageLoop() {
  DCHECK(!is_browser_ || BrowserThread::CurrentlyOn(BrowserThread::UI));
  
  
  uv_async_init(uv_loop_, &dummy_uv_handle_, UvNoOp);
  
  uv_sem_init(&embed_sem_, 0);
  uv_thread_create(&embed_thread_, EmbedThreadRunner, this);
}
void NodeBindings::RunMessageLoop() {