Add ScopedObjCClassSwizzler in base/mac, absorbs objc_method_swizzle and ScopedClassSwizzler

ui/events/test/cocoa_test_event_utils.h

 // Copyright 2014 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 UI_EVENTS_TEST_COCOA_TEST_EVENT_UTILS_H_
 #define UI_EVENTS_TEST_COCOA_TEST_EVENT_UTILS_H_
 
 #include <utility>
 
 #import <objc/objc-class.h>
 
 #include "base/basictypes.h"
 
-// Within a given scope, replace the selector |selector| on |target| with that
-// from |source|.
-class ScopedClassSwizzler {
- public:
-  ScopedClassSwizzler(Class target, Class source, SEL selector);
-  ~ScopedClassSwizzler();
-
- private:
-  Method old_selector_impl_;
-  Method new_selector_impl_;
-
-  DISALLOW_COPY_AND_ASSIGN(ScopedClassSwizzler);
-};
-
 namespace cocoa_test_event_utils {
 
 // Create synthetic mouse events for testing. Currently these are very
 // basic, flesh out as needed.  Points are all in window coordinates;
 // where the window is not specified, coordinate system is undefined
 // (but will be repeated when the event is queried).
 NSEvent* MouseEventWithType(NSEventType type, NSUInteger modifiers);
 NSEvent* MouseEventAtPoint(NSPoint point, NSEventType type,
                            NSUInteger modifiers);
 NSEvent* LeftMouseDownAtPoint(NSPoint point);
@@ skipping 20 matching lines @@
 
 // Returns a mouse enter/exit event with the given type.
 NSEvent* EnterExitEventWithType(NSEventType event_type);
 
 // Return an "other" event with the given type.
 NSEvent* OtherEventWithType(NSEventType event_type);
 
 }  // namespace cocoa_test_event_utils
 
 #endif  // UI_EVENTS_TEST_COCOA_TEST_EVENT_UTILS_H_