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### Preflight Checklist
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* [x] I have read the [Contributing Guidelines](https://github.com/electron/electron/blob/master/CONTRIBUTING.md) for this project.
* [x] I agree to follow the [Code of Conduct](https://github.com/electron/electron/blob/master/CODE_OF_CONDUCT.md) that this project adheres to.
* [x] I have searched the issue tracker for an issue that matches the one I want to file, without success.

### Issue Details

* **Electron Version:**  9.0.0
  <!-- (output of `node_modules/.bin/electron --version`) e.g. 4.0.3 -->
* **Operating System:** Windows 10 (1904)
  <!-- (Platform and Version) e.g. macOS 10.13.6 / Windows 10 (1803) / Ubuntu 18.04 x64 -->
* **Last Known Working Electron version:** 8.2.0
  <!-- (if applicable) e.g. 3.1.0 -->

### Expected Behavior
<!-- A clear and concise description of what you expected to happen. -->
Setting BrowserWindow webPreferences: { webSecurity: false } should disable the CORS policy

### Actual Behavior
<!-- A clear and concise description of what actually happened. -->
Although I am receiving the electron security warnings for "Disabled webSecurity","allowRunningInsecureContent" and "Insecure Content-Security-Policy" in the console I am still getting COR policy errors on my requests.

**Here is an example:**

Access to XMLHttpRequest at 'http://localhost:8080/users/login' from origin 'http://localhost:3000' has been blocked by CORS policy: Response to preflight request doesn't pass access control check: No 'Access-Control-Allow-Origin' header is present on the requested resource.

shell/browser/electron_browser_client.cc
->RegisterBrowserInterfaceBindersForFrame(map, render_frame_host,
                                                extension);
#endif
}
#if defined(OS_LINUX)
void ElectronBrowserClient::GetAdditionalMappedFilesForChildProcess(
    const base::CommandLine& command_line,
    int child_process_id,
    content::PosixFileDescriptorInfo* mappings) {
  int crash_signal_fd = GetCrashSignalFD(command_line);
  if (crash_signal_fd >= 0) {
    mappings->Share(service_manager::kCrashDumpSignal, crash_signal_fd);
  }
}
#endif
std::unique_ptr<content::LoginDelegate>
ElectronBrowserClient::CreateLoginDelegate(
    const net::AuthChallengeInfo& auth_info,
    content::WebContents* web_contents,
    const content::GlobalRequestID& request_id,
    bool is_main_frame,
    const GURL& url,
    scoped_refptr<net::HttpResponseHeaders> response_headers,
    bool first_auth_attempt,
    LoginAuthRequiredCallback auth_required_callback) {
  return std::make_unique<LoginHandler>(
      auth_info, web_contents, is_main_frame, url, response_headers,
      first_auth_attempt, std::move(auth_required_callback));
}
std::vector<std::unique_ptr<blink::URLLoaderThrottle>>