Destroy tooltip manager if the native window is destroyed.

views/widget/tooltip_manager_views.h

Index: views/widget/tooltip_manager_views.h
diff --git a/views/widget/tooltip_manager_views.h b/views/widget/tooltip_manager_views.h
index d98914b83a7b66937d22bc77e2e8d989bfadd284..3d22662fce6ca6dee3ec656fd422b0f37aeb331d 100644
--- a/views/widget/tooltip_manager_views.h
+++ b/views/widget/tooltip_manager_views.h
@@ -27,8 +27,7 @@ class Widget;
 
 // TooltipManager implementation for Views.
 class TooltipManagerViews : public TooltipManager,
-                            public MessageLoopForUI::Observer,
-                            public Widget::Observer {
+                            public MessageLoopForUI::Observer {
  public:
   explicit TooltipManagerViews(views::View* root_view);
   virtual ~TooltipManagerViews();
@@ -49,9 +48,6 @@ class TooltipManagerViews : public TooltipManager,
   virtual void DidProcessEvent(const base::NativeEvent& event) OVERRIDE;
 #endif
 
-  // Widget::Observer
-  virtual void OnWidgetClosing(Widget* widget) OVERRIDE;
-
  private:
   void TooltipTimerFired();
   View* GetViewForTooltip(int x, int y, bool for_keyboard);
@@ -84,9 +80,6 @@ class TooltipManagerViews : public TooltipManager,
   gfx::Point curr_mouse_pos_;
   base::RepeatingTimer<TooltipManagerViews> tooltip_timer_;
 
-  // true when the widget that owns us has closed.
-  bool widget_closed_;
-
   DISALLOW_COPY_AND_ASSIGN(TooltipManagerViews);
 };