### 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 for an issue that matches the one I want to file, without success.

### Issue Details

* **Electron Version:** 10.1.3
* **Operating System:** Windows 10
* **Last Known Working Electron version:** 10.1.2

### Expected Behavior
I expect that a BrowserView that's set up to auto resize, will do so

### Actual Behavior
No auto-resizing happens

### To Reproduce
1. start the app below
2. when the page loads in the browserview, resize the window
3. notice the black background. browser view doesn't resize

main.js:
```
const { app, BrowserWindow, BrowserView } = require('electron')

async function createWindow() {
  const mainWindow = new BrowserWindow({ backgroundColor: "#000" });
  const view = new BrowserView();
  mainWindow.setBrowserView(view);

  const contentBounds = mainWindow.getContentBounds();
  view.setBounds({ x: 0, y: 0, width: contentBounds.width, height: contentBounds.height });
  view.setAutoResize({ width: true, height: true });

  await view.webContents.loadURL("https://google.com");
}

app.on('ready', createWindow)
```
shell/browser/native_browser_view_views.cc
auto* iwc_view = GetInspectableWebContentsView();
  if (!iwc_view)
    return;
  auto* view = iwc_view->GetView();
  view->SetBoundsRect(bounds);
  ResetAutoResizeProportions();
}
gfx::Rect NativeBrowserViewViews::GetBounds() {
  auto* iwc_view = GetInspectableWebContentsView();
  if (!iwc_view)
    return gfx::Rect();
  return iwc_view->GetView()->bounds();
}
void NativeBrowserViewViews::SetBackgroundColor(SkColor color) {
  auto* iwc_view = GetInspectableWebContentsView();
  if (!iwc_view)
    return;
  auto* view = iwc_view->GetView();
  view->SetBackground(views::CreateSolidBackground(color));
  view->SchedulePaint();
}
NativeBrowserView* NativeBrowserView::Create(
    InspectableWebContents* inspectable_web_contents) {
  return new NativeBrowserViewViews(inspectable_web_contents);
}
}