* 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
const int kMenuBarHeight = 20;
#else
const int kMenuBarHeight = 25;
#endif
#if defined(OS_WIN)
gfx::Rect SubtractBorderSize(gfx::Rect bounds) {
  gfx::Point borderSize = gfx::Point(
      GetSystemMetrics(SM_CXSIZEFRAME) - 1,   
      GetSystemMetrics(SM_CYSIZEFRAME) - 1);  
  gfx::Point dpiAdjustedSize =
      display::win::ScreenWin::ScreenToDIPPoint(borderSize);
  bounds.set_x(bounds.x() + dpiAdjustedSize.x());
  bounds.set_y(bounds.y() + dpiAdjustedSize.y());
  bounds.set_width(bounds.width() - 2 * dpiAdjustedSize.x());
  bounds.set_height(bounds.height() - 2 * dpiAdjustedSize.y());
  return bounds;
}
void FlipWindowStyle(HWND handle, bool on, DWORD flag) {
  DWORD style = ::GetWindowLong(handle, GWL_STYLE);
  if (on)
    style |= flag;
  else
    style &= ~flag;
  ::SetWindowLong(handle, GWL_STYLE, style);
}
#endif
bool IsAltKey(const content::NativeWebKeyboardEvent& event) {
  return event.windowsKeyCode == ui::VKEY_MENU;
}
bool IsAltModifier(const content::NativeWebKeyboardEvent& event) {