Remove PrefObserver usage, batch 3.

chrome/browser/content_settings/content_settings_policy_provider.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 CHROME_BROWSER_CONTENT_SETTINGS_CONTENT_SETTINGS_POLICY_PROVIDER_H_
 #define CHROME_BROWSER_CONTENT_SETTINGS_CONTENT_SETTINGS_POLICY_PROVIDER_H_
 
 // A content settings provider that takes its settings out of policies.
 
 #include <vector>
 
 #include "base/basictypes.h"
 #include "base/prefs/public/pref_change_registrar.h"
-#include "base/prefs/public/pref_observer.h"
 #include "base/synchronization/lock.h"
 #include "chrome/browser/content_settings/content_settings_observable_provider.h"
 #include "chrome/browser/content_settings/content_settings_origin_identifier_value_map.h"
 
 class PrefService;
 
 namespace content_settings {
 
 // PolicyProvider that provides managed content-settings.
-class PolicyProvider : public ObservableProvider,
-                       public PrefObserver {
+class PolicyProvider : public ObservableProvider {
  public:
   explicit PolicyProvider(PrefService* prefs);
   virtual ~PolicyProvider();
   static void RegisterUserPrefs(PrefService* prefs);
 
   // ProviderInterface implementations.
   virtual RuleIterator* GetRuleIterator(
       ContentSettingsType content_type,
       const ResourceIdentifier& resource_identifier,
       bool incognito) const OVERRIDE;
 
   virtual bool SetWebsiteSetting(
       const ContentSettingsPattern& primary_pattern,
       const ContentSettingsPattern& secondary_pattern,
       ContentSettingsType content_type,
       const ResourceIdentifier& resource_identifier,
       Value* value) OVERRIDE;
 
   virtual void ClearAllContentSettingsRules(
       ContentSettingsType content_type) OVERRIDE;
 
   virtual void ShutdownOnUIThread() OVERRIDE;
 
-  // PrefObserver implementation.
-  virtual void OnPreferenceChanged(PrefServiceBase* service,
-                                   const std::string& pref_name) OVERRIDE;
-
  private:
   // Reads the policy managed default settings.
   void ReadManagedDefaultSettings();
 
+  // Callback for preference changes.
+  void OnPreferenceChanged(const std::string& pref_name);
+
   // Reads the policy controlled default settings for a specific content type.
   void UpdateManagedDefaultSetting(ContentSettingsType content_type);
 
   void ReadManagedContentSettings(bool overwrite);
 
   void GetContentSettingsFromPreferences(OriginIdentifierValueMap* rules);
 
   void GetAutoSelectCertificateSettingsFromPreferences(
       OriginIdentifierValueMap* value_map);
 
   void ReadManagedContentSettingsTypes(ContentSettingsType content_type);
 
   OriginIdentifierValueMap value_map_;
 
   PrefService* prefs_;
 
   PrefChangeRegistrar pref_change_registrar_;
 
   // Used around accesses to the |value_map_| object to guarantee
   // thread safety.
   mutable base::Lock lock_;
 
   DISALLOW_COPY_AND_ASSIGN(PolicyProvider);
 };
 
 }  // namespace content_settings
 
 #endif  // CHROME_BROWSER_CONTENT_SETTINGS_CONTENT_SETTINGS_POLICY_PROVIDER_H_