Add support for rect-based event targeting in views

ui/views/view.h

Index: ui/views/view.h
diff --git a/ui/views/view.h b/ui/views/view.h
index d6158534bfde399184b68eb10278b4aba6af363e..29c8c271e2db96e2ada1dd525b8a6319268e2f6a 100644
--- a/ui/views/view.h
+++ b/ui/views/view.h
@@ -559,12 +559,20 @@ class VIEWS_EXPORT View : public ui::LayerDelegate,
   static bool get_use_acceleration_when_possible();
 
   // Input ---------------------------------------------------------------------
-  // The points (and mouse locations) in the following functions are in the
-  // view's coordinates, except for a RootView.
+  // The points, rects, mouse locations, and touch locations in the following
+  // functions are in the view's coordinates, except for a RootView.
 
-  // Returns the deepest visible descendant that contains the specified point
-  // and supports event handling.
-  virtual View* GetEventHandlerForPoint(const gfx::Point& point);
+  // Convenience functions which calls into GetEventHandler() with
+  // a 1x1 rect centered at |point|.
+  View* GetEventHandlerForPoint(const gfx::Point& point);
+
+  // If point-based targeting should be used, return the deepest visible
+  // descendant that contains the center point of |rect|.
+  // If rect-based targeting (i.e., fuzzing) should be used, return the
+  // closest visible descendant having at least kRectTargetOverlap of
+  // its area covered by |rect|. If no such descendant exists, return the
+  // deepest visible descendant that contains the center point of |rect|.
+  virtual View* GetEventHandlerForRect(const gfx::Rect& rect);
 
   // Returns the deepest visible descendant that contains the specified point
   // and supports tooltips. If the view does not contain the point, returns
@@ -1118,6 +1126,16 @@ class VIEWS_EXPORT View : public ui::LayerDelegate,
 
   // Input ---------------------------------------------------------------------
 
+  // Specifies the source of the region used in a hit test.
+  // HIT_TEST_SOURCE_MOUSE indicates the hit test is being performed with a
+  // single point and HIT_TEST_SOURCE_TOUCH indicates the hit test is being
+  // performed with a rect larger than a single point. This value can be used,
+  // for example, to add extra padding or change the shape of the hit test mask.
+  enum HitTestSource {
+    HIT_TEST_SOURCE_MOUSE,
+    HIT_TEST_SOURCE_TOUCH
+  };
+
   // Called by HitTestRect() to see if this View has a custom hit test mask. If
   // the return value is true, GetHitTestMask() will be called to obtain the
   // mask. Default value is false, in which case the View will hit-test against
@@ -1126,7 +1144,8 @@ class VIEWS_EXPORT View : public ui::LayerDelegate,
 
   // Called by HitTestRect() to retrieve a mask for hit-testing against.
   // Subclasses override to provide custom shaped hit test regions.
-  virtual void GetHitTestMask(gfx::Path* mask) const;
+  virtual void GetHitTestMask(gfx::Path* mask,
+      HitTestSource source = HIT_TEST_SOURCE_MOUSE) const;
 
   virtual DragInfo* GetDragInfo();