### 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
std::u16string device_name;
  options.Get("deviceName", &device_name);
  if (!device_name.empty() && !IsDeviceNameValid(device_name)) {
    gin_helper::ErrorThrower(args->isolate())
        .ThrowError("webContents.print(): Invalid deviceName provided.");
    return;
  }
  int scale_factor = 100;
  options.Get("scaleFactor", &scale_factor);
  settings.SetIntKey(printing::kSettingScaleFactor, scale_factor);
  int pages_per_sheet = 1;
  options.Get("pagesPerSheet", &pages_per_sheet);
  settings.SetIntKey(printing::kSettingPagesPerSheet, pages_per_sheet);
   True if the user wants to print with collate.
  bool collate = true;
  options.Get("collate", &collate);
  settings.SetBoolKey(printing::kSettingCollate, collate);
   The number of individual copies to print
  int copies = 1;
  options.Get("copies", &copies);
  settings.SetIntKey(printing::kSettingCopies, copies);
   Strings to be printed as headers and footers if requested by the user.
  std::string header;
  options.Get("header", &header);
  std::string footer;
  options.Get("footer", &footer);
  if (!(header.empty() && footer.empty())) {
    settings.SetBoolKey(printing::kSettingHeaderFooterEnabled, true);
    settings.SetStringKey(printing::kSettingHeaderFooterTitle, header);
    settings.SetStringKey(printing::kSettingHeaderFooterURL, footer);