### 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
use_content_size_)
    size = ContentBoundsToWindowBounds(gfx::Rect(size)).size();
  widget()->CenterWindow(size);
#if defined(OS_WIN)
  
  if (fullscreen)
    last_window_state_ = ui::SHOW_STATE_FULLSCREEN;
  else
    last_window_state_ = ui::SHOW_STATE_NORMAL;
#endif
#if defined(OS_LINUX)
  
  aura::Window* window = GetNativeWindow();
  if (window)
    window->AddPreTargetHandler(this);
#endif
}
NativeWindowViews::~NativeWindowViews() {
  widget()->RemoveObserver(this);
#if defined(OS_WIN)
  
  SetForwardMouseMessages(false);
#endif
#if defined(OS_LINUX)
  aura::Window* window = GetNativeWindow();
  if (window)
    window->RemovePreTargetHandler(this);
#endif
}
void NativeWindowViews::SetGTKDarkThemeEnabled(bool use_dark_theme) {