events: Update mouse-event handlers to not return EventResult.

ui/base/events/event_target.h

 // Copyright (c) 2012 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_BASE_EVENTS_EVENT_TARGET_H_
 #define UI_BASE_EVENTS_EVENT_TARGET_H_
 
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "ui/base/events/event_handler.h"
@@ skipping 56 matching lines @@
   void RemovePostTargetHandler(EventHandler* handler);
 
  protected:
   void set_target_handler(EventHandler* handler) {
     target_handler_ = handler;
   }
 
   // Overridden from EventHandler:
   virtual void OnEvent(Event* event) OVERRIDE;
   virtual void OnKeyEvent(KeyEvent* event) OVERRIDE;
-  virtual EventResult OnMouseEvent(MouseEvent* event) OVERRIDE;
+  virtual void OnMouseEvent(MouseEvent* event) OVERRIDE;
   virtual void OnScrollEvent(ScrollEvent* event) OVERRIDE;
   virtual void OnTouchEvent(TouchEvent* event) OVERRIDE;
   virtual void OnGestureEvent(GestureEvent* event) OVERRIDE;
 
  private:
   friend class EventDispatcher;
 
   // Returns the list of handlers that should receive the event before the
   // target. The handlers from the outermost target are first in the list, and
   // the handlers on |this| are the last in the list.
   void GetPreTargetHandlers(EventHandlerList* list);
 
   // Returns the list of handlers that should receive the event after the
   // target. The handlers from the outermost target are last in the list, and
   // the handlers on |this| are the first in the list.
   void GetPostTargetHandlers(EventHandlerList* list);
 
   EventHandlerList pre_target_list_;
   EventHandlerList post_target_list_;
   EventHandler* target_handler_;
 
   DISALLOW_COPY_AND_ASSIGN(EventTarget);
 };
 
 }  // namespace ui
 
 #endif  // UI_BASE_EVENTS_EVENT_TARGET_H_