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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
base::FilePath path;
  if (base::PathService::Get(base::DIR_HOME, &path))
    path = path.Append(FILE_PATH_LITERAL("Downloads"));
  return path;
}
scoped_refptr<network::SharedURLLoaderFactory>
ElectronBrowserClient::GetSystemSharedURLLoaderFactory() {
  if (!g_browser_process)
    return nullptr;
  return g_browser_process->shared_url_loader_factory();
}
void ElectronBrowserClient::OnNetworkServiceCreated(
    network::mojom::NetworkService* network_service) {
  if (!g_browser_process)
    return;
  g_browser_process->system_network_context_manager()->OnNetworkServiceCreated(
      network_service);
}
std::vector<base::FilePath>
ElectronBrowserClient::GetNetworkContextsParentDirectory() {
  base::FilePath user_data_dir;
  base::PathService::Get(DIR_USER_DATA, &user_data_dir);
  DCHECK(!user_data_dir.empty());
  return {user_data_dir};
}
std::string ElectronBrowserClient::GetProduct() {