Move creation and ownership of HostZoomMap to content instead of having every embedder do this.

content/browser/host_zoom_map_impl.h

 // Copyright (c) 2011 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_BROWSER_HOST_ZOOM_MAP_IMPL_H_
 #define CONTENT_BROWSER_HOST_ZOOM_MAP_IMPL_H_
 #pragma once
 
 #include <map>
 #include <string>
 #include <vector>
 
 #include "base/compiler_specific.h"
 #include "base/message_loop_helpers.h"
+#include "base/supports_user_data.h"
 #include "base/synchronization/lock.h"
 #include "content/public/browser/host_zoom_map.h"
 #include "content/public/browser/notification_observer.h"
 #include "content/public/browser/notification_registrar.h"
 
 // HostZoomMap needs to be deleted on the UI thread because it listens
 // to notifications on there (and holds a NotificationRegistrar).
 class CONTENT_EXPORT HostZoomMapImpl
     : public NON_EXPORTED_BASE(content::HostZoomMap),
-      public content::NotificationObserver {
+      public content::NotificationObserver,
+      public base::SupportsUserData::Data {
  public:
   HostZoomMapImpl();
 
   // HostZoomMap implementation:
   virtual void CopyFrom(HostZoomMap* copy) OVERRIDE;
   virtual double GetZoomLevel(const std::string& host) const OVERRIDE;
   virtual void SetZoomLevel(std::string host, double level) OVERRIDE;
   virtual double GetDefaultZoomLevel() const OVERRIDE;
   virtual void SetDefaultZoomLevel(double level) OVERRIDE;
 
@@ skipping 40 matching lines @@
   // Used around accesses to |host_zoom_levels_|, |default_zoom_level_| and
   // |temporary_zoom_levels_| to guarantee thread safety.
   mutable base::Lock lock_;
 
   content::NotificationRegistrar registrar_;
 
   DISALLOW_COPY_AND_ASSIGN(HostZoomMapImpl);
 };
 
 #endif  // CONTENT_BROWSER_HOST_ZOOM_MAP_IMPL_H_