As in topic. API currently offers fixed ratio only for Mac but not for Windows
shell/browser/ui/views/frameless_view.cc
bool can_ever_resize = frame_->widget_delegate()
                             ? frame_->widget_delegate()->CanResize()
                             : false;
  
  
  int resize_border = frame_->IsMaximized() || frame_->IsFullscreen()
                          ? 0
                          : kResizeInsideBoundsSize;
  return GetHTComponentForFrame(point, resize_border, resize_border,
                                kResizeAreaCornerSize, kResizeAreaCornerSize,
                                can_ever_resize);
}
gfx::Rect FramelessView::GetBoundsForClientView() const {
  return bounds();
}
gfx::Rect FramelessView::GetWindowBoundsForClientBounds(
    const gfx::Rect& client_bounds) const {
  gfx::Rect window_bounds = client_bounds;
  
  
  
  if (window_bounds.IsEmpty()) {
    window_bounds.set_width(1);
    window_bounds.set_height(1);
  }
  return window_bounds;
}
int FramelessView::NonClientHitTest(const gfx::Point& cursor) {