Introduce the MaskedViewTargeter class

ui/views/view_targeter.h

Index: ui/views/view_targeter.h
diff --git a/ui/views/view_targeter.h b/ui/views/view_targeter.h
index 4cb347685f42e0fa62c5bba8a1f6dd9b7dd180f8..8273a8aabc4df643fa0768dff6ab0da81ce80372 100644
--- a/ui/views/view_targeter.h
+++ b/ui/views/view_targeter.h
@@ -23,6 +23,11 @@ class VIEWS_EXPORT ViewTargeter : public ui::EventTargeter {
   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;