Makes mouse-hover prevent notification toasts from moving.

ui/message_center/views/message_popup_collection.h

 // Copyright (c) 2013 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_MESSAGE_CENTER_VIEWS_MESSAGE_POPUP_COLLECTION_H_
 #define UI_MESSAGE_CENTER_VIEWS_MESSAGE_POPUP_COLLECTION_H_
 
 #include <list>
 #include <map>
 
@@ skipping 40 matching lines @@
  public:
   // |parent| specifies the parent widget of the toast windows. The default
   // parent will be used for NULL.
   MessagePopupCollection(gfx::NativeView parent,
                          MessageCenter* message_center);
   virtual ~MessagePopupCollection();
 
   // Called by ToastContentsView when its window is closed.
   void RemoveToast(ToastContentsView* toast);
 
-  void OnMouseEntered();
-  void OnMouseExited();
+  // Since these events are really coming from individual toast widgets,
+  // it helps to be able to keep track of the sender.
+  void OnMouseEntered(ToastContentsView* toast_entered);
+  void OnMouseExited(ToastContentsView* toast_exited);
 
   // Invoked by toasts when they start/finish their animations.
   // While "defer counter" is greater then zero, the popup collection does
   // not perform updates. It is used to wait for various animations and user
   // actions like serial closing of the toasts, when the remaining toasts "flow
   // under the mouse".
   void IncrementDeferCounter();
   void DecrementDeferCounter();
 
   // Runs the next step in update/animate sequence, if the defer counter is not
@@ skipping 49 matching lines @@
   void RunLoopForTest();
   gfx::Rect GetToastRectAt(size_t index);
 
   gfx::NativeView parent_;
   MessageCenter* message_center_;
   Toasts toasts_;
   gfx::Rect work_area_;
 
   int defer_counter_;
 
+  // This is only used to compare with incoming events, do not assume that
+  // the toast will be valid if this pointer is non-NULL.
+  ToastContentsView* latest_toast_entered_;
+
   // Denotes a mode when user is clicking the Close button of toasts in a
   // sequence, w/o moving the mouse. We reposition the toasts so the next one
   // happens to be right under the mouse, and the user can just dispose of
   // multipel toasts by clicking. The mode ends when defer_timer_ expires.
   bool user_is_closing_toasts_by_clicking_;
   scoped_ptr<base::OneShotTimer<MessagePopupCollection> > defer_timer_;
   // The top edge to align the position of the next toast during 'close by
   // clicking" mode.
   // Only to be used when user_is_closing_toasts_by_clicking_ is true.
   int target_top_edge_;
 
   // Weak, only exists temporarily in tests.
   scoped_ptr<base::RunLoop> run_loop_for_test_;
 
   DISALLOW_COPY_AND_ASSIGN(MessagePopupCollection);
 };
 
 }  // namespace message_center
 
 #endif // UI_MESSAGE_CENTER_VIEWS_MESSAGE_POPUP_COLLECTION_H_