Remove PrefObserver usage, batch 3.

chrome/browser/content_settings/content_settings_pref_provider.h

Index: chrome/browser/content_settings/content_settings_pref_provider.h
diff --git a/chrome/browser/content_settings/content_settings_pref_provider.h b/chrome/browser/content_settings/content_settings_pref_provider.h
index 1efc5ccbf446eb16581f2c768589cfe0e5ba25d3..17fda762e96eaec5fc75ccab52ded9e3a99a1a91 100644
--- a/chrome/browser/content_settings/content_settings_pref_provider.h
+++ b/chrome/browser/content_settings/content_settings_pref_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"
@@ -27,8 +26,7 @@ namespace content_settings {
 
 // Content settings provider that provides content settings from the user
 // preference.
-class PrefProvider : public ObservableProvider,
-                     public PrefObserver {
+class PrefProvider : public ObservableProvider {
  public:
   static void RegisterUserPrefs(PrefService* prefs);
 
@@ -54,10 +52,6 @@ class PrefProvider : public ObservableProvider,
 
   virtual void ShutdownOnUIThread() OVERRIDE;
 
-  // PrefObserver implementation.
-  virtual void OnPreferenceChanged(PrefServiceBase* service,
-                                   const std::string& pref_name) OVERRIDE;
-
  private:
   friend class DeadlockCheckerThread;  // For testing.
   // Reads all content settings exceptions from the preference and load them
@@ -65,6 +59,9 @@ class PrefProvider : public ObservableProvider,
   // true.
   void ReadContentSettingsFromPref(bool overwrite);
 
+  // Callback for changes in the pref with the same name.
+  void OnContentSettingsPatternPairsChanged();
+
   // Update the preference that stores content settings exceptions and syncs the
   // value to the obsolete preference. When calling this function, |lock_|
   // should not be held, since this function will send out notifications of