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### Issue Details

* **Electron Version:**
  * Tested with 8.0.0 and v9.0.0-beta.1
* **Operating System:**
  * macOS 10.15.3 (19D76)
* **Last Known Working Electron version:**
  * 7.1.12

### Expected Behavior

`navigator.mediaDevices.enumerateDevices()` should return a list of MediaDevices with a `label` and a `deviceId` property. The `deviceId` property should stay the same across reloads and restarts.

### Actual Behavior
The `deviceId` property changes with every reload/restart.

### To Reproduce
Simply execute `navigator.mediaDevices.enumerateDevices()` in the renderer process and compare the ids of the media devices to a different execution.

See this fork for an example:
https://github.com/codedrift/electron-quick-start

```sh
$ git clone https://github.com/codedrift/electron-quick-start -b media-device-ids
$ npm install
$ npm start || electron .
```

### Additional Information
It seems to work fine in a regular Chrome 80 browser. 

shell/browser/electron_browser_client.cc
ElectronBrowserClient::CreateURLLoaderThrottles(
    const network::ResourceRequest& request,
    content::BrowserContext* browser_context,
    const base::RepeatingCallback<content::WebContents*()>& wc_getter,
    content::NavigationUIData* navigation_ui_data,
    int frame_tree_node_id) {
  DCHECK_CURRENTLY_ON(BrowserThread::UI);
  std::vector<std::unique_ptr<blink::URLLoaderThrottle>> result;
#if BUILDFLAG(ENABLE_PLUGINS) && BUILDFLAG(ENABLE_ELECTRON_EXTENSIONS)
  result.push_back(std::make_unique<PluginResponseInterceptorURLLoaderThrottle>(
      request.resource_type, frame_tree_node_id));
#endif
  return result;
}
base::flat_set<std::string>
ElectronBrowserClient::GetPluginMimeTypesWithExternalHandlers(
    content::BrowserContext* browser_context) {
  base::flat_set<std::string> mime_types;
#if BUILDFLAG(ENABLE_PLUGINS) && BUILDFLAG(ENABLE_ELECTRON_EXTENSIONS)
  auto map = PluginUtils::GetMimeTypeToExtensionIdMap(browser_context);
  for (const auto& pair : map)
    mime_types.insert(pair.first);
#endif
  return mime_types;
}
}