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

content/common/mac/scoped_sending_event.h

-// 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.
-
-#ifndef CONTENT_COMMON_MAC_SCOPED_SENDING_EVENT_H_
-#define CONTENT_COMMON_MAC_SCOPED_SENDING_EVENT_H_
-#pragma once
-
-#include "base/basictypes.h"
-#include "base/memory/scoped_nsobject.h"
-#include "base/message_pump_mac.h"
-
-// Nested event loops can pump IPC messages, including
-// script-initiated tab closes, which could release objects that the
-// nested event loop might message.  CrAppProtocol defines how to ask
-// the embedding NSApplication subclass if an event is currently being
-// handled, in which case such closes are deferred to the top-level
-// event loop.
-//
-// ScopedSendingEvent allows script-initiated event loops to work like
-// a nested event loop, as such events do not arrive via -sendEvent:.
-// CrAppControlProtocol lets ScopedSendingEvent tell the embedding
-// NSApplication what to return from -handlingSendEvent.
-
-@protocol CrAppControlProtocol<CrAppProtocol>
-- (void)setHandlingSendEvent:(BOOL)handlingSendEvent;
-@end
-
-namespace content {
-namespace mac {
-
-class ScopedSendingEvent {
- public:
-  ScopedSendingEvent();
-  ~ScopedSendingEvent();
-
- private:
-  // The NSApp in control at the time the constructor was run, to be
-  // sure the |handling_| setting is restored appropriately.
-  NSObject<CrAppControlProtocol>* app_;
-  BOOL handling_;  // Value of -[app_ handlingSendEvent] at construction.
-
-  DISALLOW_COPY_AND_ASSIGN(ScopedSendingEvent);
-};
-
-}  // namespace mac
-}  // namespace content
-
-#endif  // CONTENT_COMMON_MAC_SCOPED_SENDING_EVENT_H_