Remove the last usages of PrefObserver outside of Prefs.

chrome/browser/ui/webui/options/core_options_handler.h

Index: chrome/browser/ui/webui/options/core_options_handler.h
diff --git a/chrome/browser/ui/webui/options/core_options_handler.h b/chrome/browser/ui/webui/options/core_options_handler.h
index 8cf06f5347f60f1a03367cf936730d060ce78587..717e2f9a3d9432ede4cb466a266e53b9e3968d5e 100644
--- a/chrome/browser/ui/webui/options/core_options_handler.h
+++ b/chrome/browser/ui/webui/options/core_options_handler.h
@@ -10,7 +10,6 @@
 
 #include "base/callback.h"
 #include "base/prefs/public/pref_change_registrar.h"
-#include "base/prefs/public/pref_observer.h"
 #include "base/values.h"
 #include "chrome/browser/plugins/plugin_status_pref_setter.h"
 #include "chrome/browser/prefs/pref_service.h"
@@ -20,8 +19,7 @@ namespace options {
 
 // Core options UI handler.
 // Handles resource and JS calls common to all options sub-pages.
-class CoreOptionsHandler : public OptionsPageUIHandler,
-                           public PrefObserver {
+class CoreOptionsHandler : public OptionsPageUIHandler {
  public:
   CoreOptionsHandler();
   virtual ~CoreOptionsHandler();
@@ -32,10 +30,6 @@ class CoreOptionsHandler : public OptionsPageUIHandler,
   virtual void InitializePage() OVERRIDE;
   virtual void Uninitialize() OVERRIDE;
 
-  // PrefObserver implementation.
-  virtual void OnPreferenceChanged(PrefServiceBase* service,
-                                   const std::string& pref_name) OVERRIDE;
-
   // WebUIMessageHandler implementation.
   virtual void RegisterMessages() OVERRIDE;
 
@@ -148,6 +142,13 @@ class CoreOptionsHandler : public OptionsPageUIHandler,
   // is an array that contains a single item, the name of the metric identifier.
   void HandleUserMetricsAction(const ListValue* args);
 
+  // We need to use virtual dispatch as handling of some prefs may be
+  // finessed in subclasses.  We need to include the PrefServiceBase
+  // pointer so that subclasses can know whether we are observing the
+  // pref from the local state or not.
+  virtual void OnPreferenceChanged(PrefServiceBase* service,
+                                   const std::string& pref_name);
+
   void UpdateClearPluginLSOData();
   void UpdatePepperFlashSettingsEnabled();