Remove PrefObserver usage, batch 3.

chrome/browser/content_settings/cookie_settings.h

Index: chrome/browser/content_settings/cookie_settings.h
diff --git a/chrome/browser/content_settings/cookie_settings.h b/chrome/browser/content_settings/cookie_settings.h
index 853f1df369c7ad7daa98e62151a3096711b9a451..77f66f3cbd688c79fc3164edb458e6d8e307a596 100644
--- a/chrome/browser/content_settings/cookie_settings.h
+++ b/chrome/browser/content_settings/cookie_settings.h
@@ -11,7 +11,6 @@
 #include "base/memory/ref_counted.h"
 #include "base/memory/singleton.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/host_content_settings_map.h"
 #include "chrome/browser/profiles/refcounted_profile_keyed_service.h"
@@ -29,8 +28,7 @@ class Profile;
 // thread and read on any thread. One instance per profile.
 
 class CookieSettings
-    : public PrefObserver,
-      public RefcountedProfileKeyedService {
+    : public RefcountedProfileKeyedService {
  public:
   CookieSettings(
       HostContentSettingsMap* host_content_settings_map,
@@ -91,10 +89,6 @@ class CookieSettings
   void ResetCookieSetting(const ContentSettingsPattern& primary_pattern,
                           const ContentSettingsPattern& secondary_pattern);
 
-  // |PrefObserver| implementation.
-  virtual void OnPreferenceChanged(PrefServiceBase* service,
-                                   const std::string& pref_name) OVERRIDE;
-
   // Detaches the |CookieSettings| from all |Profile|-related objects like
   // |PrefService|. This methods needs to be called before destroying the
   // |Profile|. Afterwards, only const methods can be called.
@@ -134,6 +128,8 @@ class CookieSettings
  private:
   virtual ~CookieSettings();
 
+  void OnBlockThirdPartyCookiesChanged();
+
   // Returns true if the "block third party cookies" preference is set.
   //
   // This method may be called on any thread.