### Preflight Checklist

- [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](https://www.github.com/electron/electron/issues) for a feature request that matches the one I want to file, without success.

### Electron Version

14.0.0-beta.12

### What operating system are you using?

Windows

### Operating System Version

10.0.19042 Build 19042

### What arch are you using?

x64

### Last Known Working Electron version

13

### Expected Behavior

Window should be transparent

### Actual Behavior

Open a window with transparency enabled and delete the dom, the window will be white instead of transparent.
**Also seems like settings the backgroundColor property has no longer an effect.** I always see a white window

```
const {app, BrowserWindow} = require('electron')
const path = require("path");

function createWindow () {
	const mainWindow = new BrowserWindow({
		transparent: true,
		frame: false,
	})

	mainWindow.loadURL('https://example.com')
	mainWindow.webContents.openDevTools()
}

app.whenReady().then(createWindow)
```

### Testcase Gist URL

https://gist.github.com/e124340107f6c4a3ade8b36d98a16b9a

### Additional Information

_No response_
shell/browser/api/electron_api_web_contents.cc
load_url_params.redirect_chain = params.redirect_chain;
  load_url_params.has_user_gesture = params.user_gesture;
  load_url_params.blob_url_loader_factory = params.blob_url_loader_factory;
  load_url_params.href_translate = params.href_translate;
  load_url_params.reload_type = params.reload_type;
  if (params.post_data) {
    load_url_params.load_type =
        content::NavigationController::LOAD_TYPE_HTTP_POST;
    load_url_params.post_data = params.post_data;
  }
  source->GetController().LoadURLWithParams(load_url_params);
  return source;
}
void WebContents::BeforeUnloadFired(content::WebContents* tab,
                                    bool proceed,
                                    bool* proceed_to_fire_unload) {
  if (type_ == Type::kBrowserWindow || type_ == Type::kOffScreen ||
      type_ == Type::kBrowserView)
    *proceed_to_fire_unload = proceed;
  else
    *proceed_to_fire_unload = true;
  
  Emit("before-unload-fired", proceed);
}
void WebContents::SetContentsBounds(content::WebContents* source,
                                    const gfx::Rect& rect) {
  for (ExtendedWebContentsObserver& observer : observers_)
    observer.OnSetContentBounds(rect);
}
void WebContents::CloseContents(content::WebContents* source) {