[Mac] Move ScopedSendingEvent from content/common/mac to base/mac.

content/test/mock_chrome_application_mac.mm

-// Copyright (c) 2011 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 "content/test/mock_chrome_application_mac.h"
-
-#include "testing/gtest/include/gtest/gtest.h"
-
-@implementation MockCrControlApp
-
-- (BOOL)isHandlingSendEvent {
-  return isHandlingSendEvent_;
-}
-
-- (void)setHandlingSendEvent:(BOOL)handlingSendEvent {
-  isHandlingSendEvent_ = handlingSendEvent;
-}
-
-@end
-
-namespace mock_cr_app {
-
-void RegisterMockCrControlApp() {
-  NSApplication* app = [MockCrControlApp sharedApplication];
-  ASSERT_TRUE([app conformsToProtocol:@protocol(CrAppControlProtocol)]);
-}
-
-}  // namespace mock_cr_app