As in topic. API currently offers fixed ratio only for Mac but not for Windows
shell/browser/native_window_views.cc
if (GetNativeWindow() && GetNativeWindow()->GetHost())
    return GetNativeWindow()->GetHost()->GetAcceleratedWidget();
  else
    return gfx::kNullAcceleratedWidget;
}
NativeWindowHandle NativeWindowViews::GetNativeWindowHandle() const {
  return GetAcceleratedWidget();
}
gfx::Rect NativeWindowViews::ContentBoundsToWindowBounds(
    const gfx::Rect& bounds) const {
  if (!has_frame())
    return bounds;
  gfx::Rect window_bounds(bounds);
#if defined(OS_WIN)
  if (widget()->non_client_view()) {
    HWND hwnd = GetAcceleratedWidget();
    gfx::Rect dpi_bounds = DIPToScreenRect(hwnd, bounds);
    window_bounds = ScreenToDIPRect(
        hwnd, widget()->non_client_view()->GetWindowBoundsForClientBounds(
                  dpi_bounds));
  }
#endif
  if (root_view_->HasMenu() && root_view_->IsMenuBarVisible()) {
    int menu_bar_height = root_view_->GetMenuBarHeight();
    window_bounds.set_y(window_bounds.y() - menu_bar_height);
    window_bounds.set_height(window_bounds.height() + menu_bar_height);
  }
  return window_bounds;
}
gfx::Rect NativeWindowViews::WindowBoundsToContentBounds(