Add GrabWindowSnapshot method to mac_util class. This code is due to dmaclac...

base/mac_util_unittest.cc

-// Copyright (c) 2008 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#include "base/mac_util.h"
-
-#include <ApplicationServices/ApplicationServices.h>
-
-#include "base/file_path.h"
-#include "testing/gtest/include/gtest/gtest.h"
-#include "testing/platform_test.h"
-
-typedef PlatformTest MacUtilTest;
-
-TEST_F(MacUtilTest, TestFSRef) {
-  FSRef ref;
-  std::string path("/System/Library");
-
-  ASSERT_TRUE(mac_util::FSRefFromPath(path, &ref));
-  EXPECT_EQ(path, mac_util::PathFromFSRef(ref));
-}
-
-TEST_F(MacUtilTest, TestLibraryPath) {
-  FilePath library_dir = mac_util::GetUserLibraryPath();
-  // Make sure the string isn't empty.
-  EXPECT_FALSE(library_dir.value().empty());
-}