* Electron version: 1.7.9
* Operating system: macOS 10.13.1

### Expected behavior

If pinch-zoom is disabled via `webFrame.setVisualZoomLevelLimits(1, 1);` it should stay disabled.

### Actual behavior

Pinch zoom is possible. 

### How to reproduce

* connect an external monitor and open any electron app there, keep the macbook pro lid closed
* disconnect the external monitor
* open the lid

=> you can now pinch zoom 
atom/renderer/api/atom_api_web_frame.cc
blink::SchemeRegistry::RegisterURLSchemeAsBypassingContentSecurityPolicy(
      WTF::String::FromUTF8(scheme.data(), scheme.length()));
}
void WebFrame::RegisterURLSchemeAsPrivileged(const std::string& scheme,
                                             mate::Arguments* args) {
  
  
  
  
  bool secure = true;
  bool bypassCSP = true;
  bool allowServiceWorkers = true;
  bool supportFetchAPI = true;
  bool corsEnabled = true;
  if (args->Length() == 2) {
    mate::Dictionary options;
    if (args->GetNext(&options)) {
      options.Get("secure", &secure);
      options.Get("bypassCSP", &bypassCSP);
      options.Get("allowServiceWorkers", &allowServiceWorkers);
      options.Get("supportFetchAPI", &supportFetchAPI);
      options.Get("corsEnabled", &corsEnabled);
    }
  }
  
  WTF::String privileged_scheme(
      WTF::String::FromUTF8(scheme.data(), scheme.length()));
  if (secure) {