### Issue Details
in frameless windows 
While setting browserview style to draggable by webkit-app-region : drag. the area won't be draggable after that
and it can not move main window 
### Electron Version:
11.0.1
### Operating System:
Windows 10 (1803)
Last Known Working Electron version:
not found
### Expected Behavior
Browser view moves the main window while I set the style of the body or one of the area to
-webkit-app-region: drag;

### Actual Behavior
nothing happen in browserview after styling -webkit-app-region: drag;

I know it is mention that in 11 version it is fixed. but it still dosn't work 

### To Reproduce
https://gist.github.com/pejmanpesyan/8540aad65e7c6980c45f23e5eaafafb9

shell/browser/native_window_views.cc
return content_view() ? content_view()->GetBoundsInScreen() : gfx::Rect();
}
gfx::Size NativeWindowViews::GetContentSize() {
#if defined(OS_WIN)
  if (IsMinimized())
    return NativeWindow::GetContentSize();
#endif
  return content_view() ? content_view()->size() : gfx::Size();
}
gfx::Rect NativeWindowViews::GetNormalBounds() {
  return widget()->GetRestoredBounds();
}
void NativeWindowViews::SetContentSizeConstraints(
    const extensions::SizeConstraints& size_constraints) {
  NativeWindow::SetContentSizeConstraints(size_constraints);
#if defined(OS_WIN)
  
  
  if (!thick_frame_)
    return;
#endif
  
  
  if (widget() && widget()->widget_delegate())
    widget()->OnSizeConstraintsChanged();
  if (resizable_)
    old_size_constraints_ = size_constraints;
}
void NativeWindowViews::SetResizable(bool resizable) {