Attempt 2 at:

views/view.h

 // Copyright (c) 2010 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 VIEWS_VIEW_H_
 #define VIEWS_VIEW_H_
 
 #include "build/build_config.h"
 
 #include <algorithm>
@@ skipping 160 matching lines @@
   gfx::Rect GetBounds(PositionMirroringSettings settings) const;
 
   // Set the bounds in the parent's coordinate system.
   void SetBounds(const gfx::Rect& bounds);
   void SetBounds(int x, int y, int width, int height) {
     SetBounds(gfx::Rect(x, y, std::max(0, width), std::max(0, height)));
   }
   void SetX(int x) { SetBounds(x, y(), width(), height()); }
   void SetY(int y) { SetBounds(x(), y, width(), height()); }
 
+  // Registers this view for mouse near events (OnMouseNear and
+  // OnMouseExitedNear). Mouse near events are sent for the extended rectangle
+  // defined by the bounds of this view + |insets|.
+  void RegisterForMouseNearEvents(const gfx::Insets& insets);
+
   // Returns the left coordinate of the View, relative to the parent View,
   // which is the value of bounds_.x().
   //
   // This is the function subclasses should use whenever they need to obtain
   // the left position of one of their child views (for example, when
   // implementing View::Layout()).
   // This is equivalent to GetX(IGNORE_MIRRORING_TRANSFORMATION), but
   // inlinable.
   int x() const { return bounds_.x(); }
   int y() const { return bounds_.y(); }
@@ skipping 488 matching lines @@
   // This method is invoked when the mouse enters this control.
   //
   // Default implementation does nothing. Override as needed.
   virtual void OnMouseEntered(const MouseEvent& event);
 
   // This method is invoked when the mouse exits this control
   // The provided event location is always (0, 0)
   // Default implementation does nothing. Override as needed.
   virtual void OnMouseExited(const MouseEvent& event);
 
+  // Sent when the mouse enters the rectangle defined by this views bounds and
+  // the insets passed to RegisterForMouseNearEvents. This is only sent for
+  // views that have explicitly registered for near notification
+  // (RegisterForMouseNearEvents).
+  virtual void OnMouseNear(const MouseEvent& event) {}
+
+  // Sent when the mouse exits the rectangle defined by this views bounds and
+  // the insets passed to RegisterForMouseNearEvents. This is only sent for
+  // views that have explicitly registered for near notification
+  // (RegisterForMouseNearEvents).
+  virtual void OnMouseExitedNear(const MouseEvent& event) {}
+
   // Set the MouseHandler for a drag session.
   //
   // A drag session is a stream of mouse events starting
   // with a MousePressed event, followed by several MouseDragged
   // events and finishing with a MouseReleased event.
   //
   // This method should be only invoked while processing a
   // MouseDragged or MouseReleased event.
   //
   // All further mouse dragged and mouse up events will be sent
@@ skipping 470 matching lines @@
 
   // Propagates UpdateTooltip() to the TooltipManager for the Widget.
   // This must be invoked any time the View hierarchy changes in such a way
   // the view under the mouse differs. For example, if the bounds of a View is
   // changed, this is invoked. Similarly, as Views are added/removed, this
   // is invoked.
   void UpdateTooltip();
 
   // Recursively descends through all descendant views,
   // registering/unregistering all views that want visible bounds in root
-  // view notification.
-  static void RegisterChildrenForVisibleBoundsNotification(RootView* root,
-                                                           View* view);
-  static void UnregisterChildrenForVisibleBoundsNotification(RootView* root,
-                                                             View* view);
+  // view notification and/or mouse near events.
+  static void RegisterChildrenForRootNotifications(RootView* root, View* view);
+  static void UnregisterChildrenForRootNotifications(RootView* root,
+                                                     View* view);
+
 
   // Adds/removes view to the list of descendants that are notified any time
   // this views location and possibly size are changed.
   void AddDescendantToNotify(View* view);
   void RemoveDescendantToNotify(View* view);
 
   // Initialize the previous/next focusable views of the specified view relative
   // to the view at the specified index.
   void InitFocusSiblings(View* view, int index);
 
@@ skipping 79 matching lines @@
   scoped_ptr<ViewAccessibilityWrapper> accessibility_;
 #endif
 
   DragController* drag_controller_;
 
   // Indicates whether or not the gfx::Canvas object passed to View::Paint()
   // is going to be flipped horizontally (using the appropriate transform) on
   // right-to-left locales for this View.
   bool flip_canvas_on_paint_for_rtl_ui_;
 
+  // Insets passed to RegisterForMouseNearEvents.
+  scoped_ptr<gfx::Insets> near_insets_;
+
   // The default value for how long to wait (in ms) before showing a menu
   // button on hover. This value is used if the OS doesn't supply one.
   static const int kShowFolderDropMenuDelay;
 
   DISALLOW_COPY_AND_ASSIGN(View);
 };
 
 }  // namespace views
 
 #endif  // VIEWS_VIEW_H_