As in topic. API currently offers fixed ratio only for Mac but not for Windows
shell/browser/native_window_views.cc
if (IsVisible())
    widget()->Maximize();
  else
    widget()->native_widget_private()->Show(ui::SHOW_STATE_MAXIMIZED,
                                            gfx::Rect());
}
#endif
void NativeWindowViews::Unmaximize() {
#if defined(OS_WIN)
  if (!(::GetWindowLong(GetAcceleratedWidget(), GWL_STYLE) & WS_THICKFRAME)) {
    SetBounds(restore_bounds_, false);
    return;
  }
#endif
  widget()->Restore();
}
bool NativeWindowViews::IsMaximized() {