

### 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:**
  * 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.h
bool RendererUsesNativeWindowOpen(int process_id) const;
  bool RendererDisablesPopups(int process_id) const;
  std::string GetAffinityPreference(content::RenderFrameHost* rfh) const;
  content::SiteInstance* GetSiteInstanceFromAffinity(
      content::BrowserContext* browser_context,
      const GURL& url,
      content::RenderFrameHost* rfh) const;
  void ConsiderSiteInstanceForAffinity(content::RenderFrameHost* rfh,
                                       content::SiteInstance* site_instance);
  bool IsRendererSubFrame(int process_id) const;
  
  std::map<int, content::WebContents*> pending_processes_;
  std::map<int, base::ProcessId> render_process_host_pids_;
  std::set<int> renderer_is_subframe_;
  
  std::map<std::string, content::SiteInstance*> site_per_affinities_;
  std::unique_ptr<PlatformNotificationService> notification_service_;
  std::unique_ptr<NotificationPresenter> notification_presenter_;
  Delegate* delegate_ = nullptr;
  std::map<int, ProcessPreferences> process_preferences_;
  std::string user_agent_override_ = "";
  bool disable_process_restart_tricks_ = true;
  
  
  uint64_t next_id_ = 0;
  DISALLOW_COPY_AND_ASSIGN(ElectronBrowserClient);
};
}  
#endif