[gtk] fix zoom bubble showing up on wrong window

content/public/browser/web_contents.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 CONTENT_PUBLIC_BROWSER_WEB_CONTENTS_H_
 #define CONTENT_PUBLIC_BROWSER_WEB_CONTENTS_H_
 
 #include "base/basictypes.h"
 #include "base/callback_forward.h"
 #include "base/process_util.h"
@@ skipping 316 matching lines @@
   // such as closing the window.  The setter is maintained by TabStripModel, and
   // the getter only useful from within TAB_CLOSED notification
   virtual void SetClosedByUserGesture(bool value) = 0;
   virtual bool GetClosedByUserGesture() const = 0;
 
   // Gets the zoom level for this tab.
   virtual double GetZoomLevel() const = 0;
 
   // Gets the zoom percent for this tab.
   virtual int GetZoomPercent(bool* enable_increment,
-                             bool* enable_decrement) = 0;
+                             bool* enable_decrement) const = 0;
 
   // Opens view-source tab for this contents.
   virtual void ViewSource() = 0;
 
   virtual void ViewFrameSource(const GURL& url,
                                const std::string& content_state)= 0;
 
   // Gets the minimum/maximum zoom percent.
   virtual int GetMinimumZoomPercent() const = 0;
   virtual int GetMaximumZoomPercent() const = 0;
@@ skipping 31 matching lines @@
   // Focuses the location bar.
   virtual void SetFocusToLocationBar(bool select_all) = 0;
 
   // Does this have an opener associated with it?
   virtual bool HasOpener() const = 0;
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_BROWSER_WEB_CONTENTS_H_