* Electron version: 1.4.15
* Operating system: Windows 10

### Actual behavior

Height is oversized by exactly 8px consistently (taskbar is set to small icons).

![Alt](https://raw.githubusercontent.com/adi518/electron-frameless-maximize-test/master/issue.jpg)

### How to reproduce

https://github.com/adi518/electron-frameless-maximize-test
atom/browser/native_window_views.cc
if (enable) {
    --disable_count_;
    if (disable_count_ != 0)
      return;
  } else {
    ++disable_count_;
    if (disable_count_ != 1)
      return;
  }
#if defined(OS_WIN)
  ::EnableWindow(GetAcceleratedWidget(), enable);
#elif defined(USE_X11)
  views::DesktopWindowTreeHostX11* tree_host =
      views::DesktopWindowTreeHostX11::GetHostForXID(GetAcceleratedWidget());
  if (enable) {
    tree_host->RemoveEventRewriter(event_disabler_.get());
    event_disabler_.reset();
  } else {
    event_disabler_.reset(new EventDisabler);
    tree_host->AddEventRewriter(event_disabler_.get());
  }
#endif
}
void NativeWindowViews::OnWidgetActivationChanged(