### Preflight Checklist
<!-- Please ensure you've completed the following steps by replacing [ ] with [x]-->

* [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:**
  * 9.1.1
  * 10.0.0-beta.4
* **Operating System:**
  * Linux x64

### Expected Behavior

Don't crash when `nodeIntegrationInWorker` is `true` and a service worker is being registered. :slightly_smiling_face:

### Actual Behavior

A crash occurs once the service worker is attempted to be registered (blank page, DevTools disconnects).

### To Reproduce

Attempt to register a service worker with `nodeIntegrationInWorker` set to `true`.

```sh
$ git clone https://github.com/lgrahl/electron-node-integration-service-worker-crash
$ npm install
$ npm start
```

Commit https://github.com/lgrahl/electron-node-integration-service-worker-crash/commit/97b14f2c599bfd25ce416b8a7ee91d9122bbfe2c
shell/browser/electron_browser_client.cc
if (!BrowserThread::IsThreadInitialized(BrowserThread::IO) ||
      !base::PostTask(
          FROM_HERE, {BrowserThread::IO},
          base::BindOnce(&SetApplicationLocaleOnIOThread, locale))) {
    g_io_thread_application_locale.Get() = locale;
  }
  *g_application_locale = locale;
}
ElectronBrowserClient::ElectronBrowserClient() {
  DCHECK(!g_browser_client);
  g_browser_client = this;
}
ElectronBrowserClient::~ElectronBrowserClient() {
  DCHECK(g_browser_client);
  g_browser_client = nullptr;
}
content::WebContents* ElectronBrowserClient::GetWebContentsFromProcessID(
    int process_id) {
  
  
  const auto iter = pending_processes_.find(process_id);
  if (iter != std::end(pending_processes_))
    return iter->second;
  
  
  return WebContentsPreferences::GetWebContentsFromProcessID(process_id);
}
bool ElectronBrowserClient::ShouldForceNewSiteInstance(