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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
#include "extensions/browser/process_map.h"
#include "extensions/browser/url_loader_factory_manager.h"
#include "extensions/common/api/mime_handler.mojom.h"
#include "extensions/common/constants.h"
#include "extensions/common/extension.h"
#include "extensions/common/switches.h"
#include "shell/browser/extensions/electron_extension_message_filter.h"
#include "shell/browser/extensions/electron_extension_system.h"
#include "shell/browser/extensions/electron_extension_web_contents_observer.h"
#endif
#if BUILDFLAG(ENABLE_PLUGINS)
#include "chrome/browser/plugins/plugin_response_interceptor_url_loader_throttle.h"  
#include "shell/browser/plugins/plugin_utils.h"
#endif
#if defined(OS_MAC)
#include "content/common/mac_helpers.h"
#include "content/public/common/child_process_host.h"
#endif
#if defined(OS_LINUX) && !defined(MAS_BUILD)
#include "base/debug/leak_annotations.h"
#include "components/crash/content/browser/crash_handler_host_linux.h"
#include "components/crash/core/app/breakpad_linux.h"  
#include "components/crash/core/app/crash_switches.h"  
#include "components/crash/core/app/crashpad.h"        
#endif
using content::BrowserThread;
namespace electron {
namespace {
bool g_suppress_renderer_process_restart = false;
bool IsSameWebSite(content::BrowserContext* browser_context,