Add notification mechanism when BrowserActionButton's icon has been updated.

ui/views/controls/menu/menu_item_view.h

Index: ui/views/controls/menu/menu_item_view.h
diff --git a/ui/views/controls/menu/menu_item_view.h b/ui/views/controls/menu/menu_item_view.h
index bb1ae266193a1711073eb113c23ce63bf089a8b2..dd6b936907e2a526617652f1f05644361d4178d1 100644
--- a/ui/views/controls/menu/menu_item_view.h
+++ b/ui/views/controls/menu/menu_item_view.h
@@ -61,6 +61,18 @@ class SubmenuView;
 
 class VIEWS_EXPORT MenuItemView : public View {
  public:
+  // The LifecycleObserver will receive a notification when the MenuItemView has
+  // been deleted.
+  class LifecycleObserver {
+   public:
+    virtual ~LifecycleObserver() {}
+    virtual void OnDeleted(MenuItemView* view) = 0;
+  };
+
+  void set_lifecycle_observer(LifecycleObserver* lifecycle_observer) {
+    lifecycle_observer_ = lifecycle_observer;
+  }
+
   friend class MenuController;
 
   // The menu item view's class name.
@@ -526,6 +538,10 @@ class VIEWS_EXPORT MenuItemView : public View {
   // containing other elements.
   bool use_right_margin_;
 
+  // The observer that we need to notify when the menu item view has been
+  // deleted.
+  LifecycleObserver* lifecycle_observer_;
+
   DISALLOW_COPY_AND_ASSIGN(MenuItemView);
 };