Don't re-use a zoom bubble unless it has the same web-contents.

chrome/browser/ui/views/location_bar/zoom_bubble_view.h

 // Copyright (c) 2012 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 CHROME_BROWSER_UI_VIEWS_LOCATION_BAR_ZOOM_BUBBLE_VIEW_H_
 #define CHROME_BROWSER_UI_VIEWS_LOCATION_BAR_ZOOM_BUBBLE_VIEW_H_
 
 #include "base/basictypes.h"
 #include "base/gtest_prod_util.h"
 #include "base/timer/timer.h"
@@ skipping 99 matching lines @@
   void OnMouseExited(const ui::MouseEvent& event) override;
 
   // ui::EventHandler method.
   void OnGestureEvent(ui::GestureEvent* event) override;
 
   // views::ButtonListener method.
   void ButtonPressed(views::Button* sender, const ui::Event& event) override;
 
   // views::BubbleDelegateView method.
   void Init() override;
-  void WindowClosing() override;
 
   // content::NotificationObserver method.
   void Observe(int type,
                const content::NotificationSource& source,
                const content::NotificationDetails& details) override;
 
   // ImmersiveModeController::Observer methods.
   void OnImmersiveRevealStarted() override;
   void OnImmersiveModeControllerDestroyed() override;
 
@@ skipping 26 matching lines @@
   // Not owned.
   ImmersiveModeController* immersive_mode_controller_;
 
   // Used to register for fullscreen change notifications.
   content::NotificationRegistrar registrar_;
 
   DISALLOW_COPY_AND_ASSIGN(ZoomBubbleView);
 };
 
 #endif  // CHROME_BROWSER_UI_VIEWS_LOCATION_BAR_ZOOM_BUBBLE_VIEW_H_