### 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
const std::string& event,
    content::NavigationHandle* navigation_handle) {
  bool is_main_frame = navigation_handle->IsInMainFrame();
  int frame_tree_node_id = navigation_handle->GetFrameTreeNodeId();
  content::FrameTreeNode* frame_tree_node =
      content::FrameTreeNode::GloballyFindByID(frame_tree_node_id);
  content::RenderFrameHostManager* render_manager =
      frame_tree_node->render_manager();
  content::RenderFrameHost* frame_host = nullptr;
  if (render_manager) {
    frame_host = render_manager->speculative_frame_host();
    if (!frame_host)
      frame_host = render_manager->current_frame_host();
  }
  int frame_process_id = -1, frame_routing_id = -1;
  if (frame_host) {
    frame_process_id = frame_host->GetProcess()->GetID();
    frame_routing_id = frame_host->GetRoutingID();
  }
  bool is_same_document = navigation_handle->IsSameDocument();
  auto url = navigation_handle->GetURL();
  return Emit(event, url, is_same_document, is_main_frame, frame_process_id,
              frame_routing_id);
}
void WebContents::Message(bool internal,