### Preflight Checklist

- [X] I have read the [Contributing Guidelines](https://github.com/electron/electron/blob/main/CONTRIBUTING.md) for this project.
- [X] I agree to follow the [Code of Conduct](https://github.com/electron/electron/blob/main/CODE_OF_CONDUCT.md) that this project adheres to.
- [X] I have searched the [issue tracker](https://www.github.com/electron/electron/issues) for a feature request that matches the one I want to file, without success.

### Electron Version

14.0.1

### What operating system are you using?

macOS

### Operating System Version

macOS Big Sur 11.6.1

### What arch are you using?

x64

### Last Known Working Electron version

14.0.0

### Expected Behavior


When `BrowserView.setBackgroundColor` is called with an explicit color, expect the background to be the color selected.

When `BrowserView.setBackgroundColor` is not called, expect the background of the `BrowserView` to be transparent by default; and can see through `BrowserWindow`'s background color.



### Actual Behavior

The `BrowserView` background is always white.

### Testcase Gist URL

https://gist.github.com/kevinlinv/2de60478ffec6a2f18f1ec0fc6f5add9

### Additional Information

Here is a quick recording that reproduces the error.

https://user-images.githubusercontent.com/44967897/140694174-e27aff28-1847-4813-bc46-d9fda6569128.mp4


shell/browser/api/electron_api_web_contents.cc
"Failed to load URL: " + url.possibly_invalid_spec() +
              " with error: " + description,
          "electron");
      Emit("did-fail-load", code, description, url, is_main_frame,
           frame_process_id, frame_routing_id);
    }
  }
  content::NavigationEntry* entry = navigation_handle->GetNavigationEntry();
   This check is needed due to an issue in Chromium
   Check the Chromium issue to keep updated:
   https:bugs.chromium.org/p/chromium/issues/detail?id=1178663
   If a history entry has been made and the forward/back call has been made,
   proceed with setting the new title
  if (entry && (entry->GetTransitionType() & ui::PAGE_TRANSITION_FORWARD_BACK))
    WebContents::TitleWasSet(entry);
}
void WebContents::TitleWasSet(content::NavigationEntry* entry) {
  std::u16string final_title;
  bool explicit_set = true;
  if (entry) {
    auto title = entry->GetTitle();
    auto url = entry->GetURL();
    if (url.SchemeIsFile() && title.empty()) {
      final_title = base::UTF8ToUTF16(url.ExtractFileName());
      explicit_set = false;
    } else {
      final_title = title;
    }
  } else {
    final_title = ontents()->GetTitle();