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
#include "atom/common/node_bindings.h"
#include <string>
#include <vector>
#include "atom/common/api/event_emitter_caller.h"
#include "atom/common/api/locker.h"
#include "atom/common/atom_command_line.h"
#include "atom/common/native_mate_converters/file_path_converter.h"
#include "base/command_line.h"
#include "base/base_paths.h"
#include "base/environment.h"
#include "base/files/file_path.h"
#include "base/message_loop/message_loop.h"
#include "base/path_service.h"
#include "content/public/browser/browser_thread.h"
#include "content/public/common/content_paths.h"
#include "native_mate/dictionary.h"
#include "atom/common/node_includes.h"
using content::BrowserThread;
#define REFERENCE_MODULE(name) \
  extern "C" void _register_ ## name(void); \
  void (*fp_register_ ## name)(void) = _register_ ## name
REFERENCE_MODULE(atom_browser_app);
REFERENCE_MODULE(atom_browser_auto_updater);
REFERENCE_MODULE(atom_browser_content_tracing);
REFERENCE_MODULE(atom_browser_dialog);
REFERENCE_MODULE(atom_browser_debugger);
REFERENCE_MODULE(atom_browser_desktop_capturer);
REFERENCE_MODULE(atom_browser_download_item);