### 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
Emit("close");
  auto* autofill_driver_factory =
      AutofillDriverFactory::FromWebContents(ontents());
  if (autofill_driver_factory) {
    autofill_driver_factory->CloseAllPopups();
  }
  for (ExtendedWebContentsObserver& observer : observers_)
    observer.OnCloseContents();
}
void WebContents::ActivateContents(content::WebContents* source) {
  for (ExtendedWebContentsObserver& observer : observers_)
    observer.OnActivateContents();
}
void WebContents::UpdateTargetURL(content::WebContents* source,
                                  const GURL& url) {
  Emit("update-target-url", url);
}
bool WebContents::HandleKeyboardEvent(
    content::WebContents* source,
    const content::NativeWebKeyboardEvent& event) {
  if (type_ == Type::kWebView && embedder_) {
    
    return embedder_->HandleKeyboardEvent(source, event);
  } else {
    return PlatformHandleKeyboardEvent(source, event);
  }
}
#if !defined(OS_MAC)
bool WebContents::PlatformHandleKeyboardEvent(