Introduce XGetImage() for GrabWindowSnapshot() in ChromeOS.

BUG=119492
TEST=manually done

Review URL: https://chromiumcodereview.appspot.com/10386124

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@137556 0039d316-1c4b-4281-b951-d872f2087c98
gfx::Point RootWindowHostWin::QueryMouseLocation() {
  POINT pt;
  GetCursorPos(&pt);
  ScreenToClient(hwnd(), &pt);
  const gfx::Size size = GetBounds().size();
  return gfx::Point(max(0, min(size.width(), static_cast<int>(pt.x))),
                    max(0, min(size.height(), static_cast<int>(pt.y))));
}

gfx::Point RootWindowHostWin::QueryMouseLocation() {
  POINT pt;
  GetCursorPos(&pt);
  ScreenToClient(hwnd(), &pt);
  const gfx::Size size = GetBounds().size();
  return gfx::Point(max(0, min(size.width(), static_cast<int>(pt.x))),
                    max(0, min(size.height(), static_cast<int>(pt.y))));
}
