Add support for MouseEnter/MouseExit event types to be sent to aura::Windows.

ui/aura/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 UI_AURA_EVENT_H_
 #define UI_AURA_EVENT_H_
 #pragma once
 
 #include "base/basictypes.h"
 #include "base/time.h"
@@ skipping 20 matching lines @@
  public:
   const NativeEvent& native_event() const { return native_event_; }
   ui::EventType type() const { return type_; }
   const base::Time& time_stamp() const { return time_stamp_; }
   int flags() const { return flags_; }
 
  protected:
   Event(ui::EventType type, int flags);
   Event(NativeEvent native_event, ui::EventType type, int flags);
   Event(const Event& copy);
+  void set_type(ui::EventType type) { type_ = type; }
 
  private:
   void operator=(const Event&);
 
   // Safely initializes the native event members of this class.
   void Init();
   void InitWithNativeEvent(NativeEvent native_event);
 
   NativeEvent native_event_;
   ui::EventType type_;
@@ skipping 25 matching lines @@
 };
 
 class AURA_EXPORT MouseEvent : public LocatedEvent {
  public:
   explicit MouseEvent(NativeEvent native_event);
 
   // Create a new MouseEvent which is identical to the provided model.
   // If source / target windows are provided, the model location will be
   // converted from |source| coordinate system to |target| coordinate system.
   MouseEvent(const MouseEvent& model, Window* source, Window* target);
+  MouseEvent(const MouseEvent& model,
+             Window* source,
+             Window* target,
+             ui::EventType type);
 
   // Used for synthetic events in testing.
   MouseEvent(ui::EventType type, const gfx::Point& location, int flags);
 
  private:
   DISALLOW_COPY_AND_ASSIGN(MouseEvent);
 };
 
 class AURA_EXPORT KeyEvent : public Event {
  public:
   explicit KeyEvent(NativeEvent native_event);
 
   // Used for synthetic events in testing.
   KeyEvent(ui::EventType type,
            ui::KeyboardCode key_code,
            int flags);
 
   ui::KeyboardCode key_code() const { return key_code_; }
 
  private:
   ui::KeyboardCode key_code_;
 };
 
 }  // namespace aura
 
 #endif  // UI_AURA_EVENT_H_