As in topic. API currently offers fixed ratio only for Mac but not for Windows
shell/browser/native_window_views.cc
const std::vector<mojom::DraggableRegionPtr>& regions) {
  draggable_region_ = DraggableRegionsToSkRegion(regions);
}
#if defined(OS_WIN)
void NativeWindowViews::SetIcon(HICON window_icon, HICON app_icon) {
  
  window_icon_ = base::win::ScopedHICON(CopyIcon(window_icon));
  app_icon_ = base::win::ScopedHICON(CopyIcon(app_icon));
  HWND hwnd = GetAcceleratedWidget();
  SendMessage(hwnd, WM_SETICON, ICON_SMALL,
              reinterpret_cast<LPARAM>(window_icon_.get()));
  SendMessage(hwnd, WM_SETICON, ICON_BIG,
              reinterpret_cast<LPARAM>(app_icon_.get()));
}
#elif defined(OS_LINUX)
void NativeWindowViews::SetIcon(const gfx::ImageSkia& icon) {