Make sure WebContents passed to chrome_page_zoom::Zoom() have a ZoomController.

chrome/browser/ui/zoom/zoom_controller.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_ZOOM_ZOOM_CONTROLLER_H_
 #define CHROME_BROWSER_UI_ZOOM_ZOOM_CONTROLLER_H_
 
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "base/memory/scoped_ptr.h"
@@ skipping 65 matching lines @@
   // Returns which image should be loaded for the current zoom level.
   int GetResourceForZoomLevel() const;
 
   const extensions::Extension* last_extension() const {
     return last_extension_.get();
   }
 
   void AddObserver(ZoomObserver* observer);
   void RemoveObserver(ZoomObserver* observer);
 
+  // Used to set whether the zoom notification bubble can be shown when the
+  // zoom level is changed for this controller. Default behavior is to show
+  // the bubble.
+  void SetShowsNotificationBubble(bool can_show_bubble) {
+    can_show_bubble_ = can_show_bubble;
+  }
+
   // Gets the current zoom level by querying HostZoomMap (if not in manual zoom
   // mode) or from the ZoomController local value otherwise.
   double GetZoomLevel() const;
   // Calls GetZoomLevel() then converts the returned value to a percentage
   // zoom factor.
   int GetZoomPercent() const;
 
   // Sets the zoom level through HostZoomMap.
   // Returns true on success.
   bool SetZoomLevel(double zoom_level);
@@ skipping 18 matching lines @@
   friend class ZoomControllerTest;
 
   void OnZoomLevelChanged(const content::HostZoomMap::ZoomLevelChange& change);
 
   // Updates the zoom icon and zoom percentage based on current values and
   // notifies the observer if changes have occurred. |host| may be empty,
   // meaning the change should apply to ~all sites. If it is not empty, the
   // change only affects sites with the given host.
   void UpdateState(const std::string& host);
 
+  // True if changes to zoom level can trigger the zoom notification bubble.
+  bool can_show_bubble_;
+
   // The current zoom mode.
   ZoomMode zoom_mode_;
 
   // Current zoom level.
   double zoom_level_;
 
   // Used to access the default zoom level preference.
   DoublePrefMember default_zoom_level_;
 
   scoped_ptr<ZoomChangedEventData> event_data_;
 
   // Keeps track of the extension (if any) that initiated the last zoom change
   // that took effect.
   scoped_refptr<const extensions::Extension> last_extension_;
 
   // Observer receiving notifications on state changes.
   ObserverList<ZoomObserver> observers_;
 
   content::BrowserContext* browser_context_;
 
   scoped_ptr<content::HostZoomMap::Subscription> zoom_subscription_;
 
   DISALLOW_COPY_AND_ASSIGN(ZoomController);
 };
 
 #endif  // CHROME_BROWSER_UI_ZOOM_ZOOM_CONTROLLER_H_