Introduce the MaskedViewTargeter class

ui/views/view_targeter.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_VIEWS_VIEW_TARGETER_H_
 #define UI_VIEWS_VIEW_TARGETER_H_
 
 #include "ui/events/event_targeter.h"
 #include "ui/views/views_export.h"
 
 namespace views {
 
 class View;
 
 // Contains the logic used to determine the View to which an
 // event should be dispatched. A ViewTargeter (or one of its
 // derived classes) is installed on a View to specify the
 // targeting behaviour to be used for the subtree rooted at
 // that View.
 class VIEWS_EXPORT ViewTargeter : public ui::EventTargeter {
  public:
   ViewTargeter();
   virtual ~ViewTargeter();
 
  protected:
+  // Returns the location of |event| represented as a rect. If |event| is
+  // a gesture event, its bounding box is returned. Otherwise, a 1x1 rect
+  // having its origin at the location of |event| is returned.
+  gfx::RectF BoundsForEvent(const ui::LocatedEvent& event) const;
+
   // ui::EventTargeter:
   virtual ui::EventTarget* FindTargetForEvent(ui::EventTarget* root,
                                               ui::Event* event) OVERRIDE;
   virtual ui::EventTarget* FindNextBestTarget(ui::EventTarget* previous_target,
                                               ui::Event* event) OVERRIDE;
   virtual bool SubtreeCanAcceptEvent(
       ui::EventTarget* target,
       const ui::LocatedEvent& event) const OVERRIDE;
   virtual bool EventLocationInsideBounds(
       ui::EventTarget* target,
       const ui::LocatedEvent& event) const OVERRIDE;
 
  private:
   View* FindTargetForKeyEvent(View* view, const ui::KeyEvent& key);
 
   DISALLOW_COPY_AND_ASSIGN(ViewTargeter);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_VIEW_TARGETER_H_