Remove PrefObserver usage, batch 3.

chrome/browser/content_settings/content_settings_policy_provider.h

Index: chrome/browser/content_settings/content_settings_policy_provider.h
diff --git a/chrome/browser/content_settings/content_settings_policy_provider.h b/chrome/browser/content_settings/content_settings_policy_provider.h
index 096c09b9fa254a5457a46c1dcdaffe4148c3918b..b9c2b4bfbd9d9148292d93c6b45be3b3f0593e31 100644
--- a/chrome/browser/content_settings/content_settings_policy_provider.h
+++ b/chrome/browser/content_settings/content_settings_policy_provider.h
@@ -11,7 +11,6 @@
 
 #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"
@@ -21,8 +20,7 @@ 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();
@@ -46,14 +44,13 @@ class PolicyProvider : public ObservableProvider,
 
   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);