### 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_browser_view_views.cc
InspectableWebContents* inspectable_web_contents)
    : NativeBrowserView(inspectable_web_contents) {}
NativeBrowserViewViews::~NativeBrowserViewViews() = default;
void NativeBrowserViewViews::SetAutoResizeFlags(uint8_t flags) {
  auto_resize_flags_ = flags;
  ResetAutoResizeProportions();
}
void NativeBrowserViewViews::SetAutoResizeProportions(
    const gfx::Size& window_size) {
  if ((auto_resize_flags_ & AutoResizeFlags::kAutoResizeHorizontal) &&
      !auto_horizontal_proportion_set_) {
    auto* iwc_view = GetInspectableWebContentsView();
    if (!iwc_view)
      return;
    auto* view = iwc_view->GetView();
    auto view_bounds = view->bounds();
    auto_horizontal_proportion_width_ =
        static_cast<float>(window_size.width()) /
        static_cast<float>(view_bounds.width());
    auto_horizontal_proportion_left_ = static_cast<float>(window_size.width()) /
                                       static_cast<float>(view_bounds.x());
    auto_horizontal_proportion_set_ = true;
  }