Remove content::NotificationObserver dependency from most Prefs code.

chrome/browser/browser_process_impl.h

Index: chrome/browser/browser_process_impl.h
diff --git a/chrome/browser/browser_process_impl.h b/chrome/browser/browser_process_impl.h
index 304cd7a3ac0919e2858daf4b3b4cbcecb3ece0de..5f18e625ce7f87ffa56319f0f9c9a470dffc7bbb 100644
--- a/chrome/browser/browser_process_impl.h
+++ b/chrome/browser/browser_process_impl.h
@@ -17,10 +17,10 @@
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/prefs/public/pref_change_registrar.h"
+#include "base/prefs/public/pref_observer.h"
 #include "base/threading/non_thread_safe.h"
 #include "base/timer.h"
 #include "chrome/browser/browser_process.h"
-#include "content/public/browser/notification_observer.h"
 
 class ChromeNetLog;
 class ChromeResourceDispatcherHostDelegate;
@@ -43,7 +43,7 @@ class PolicyService;
 // Real implementation of BrowserProcess that creates and returns the services.
 class BrowserProcessImpl : public BrowserProcess,
                            public base::NonThreadSafe,
-                           public content::NotificationObserver {
+                           public PrefObserver {
  public:
   // |local_state_task_runner| must be a shutdown-blocking task runner.
   BrowserProcessImpl(base::SequencedTaskRunner* local_state_task_runner,
@@ -120,10 +120,9 @@ class BrowserProcessImpl : public BrowserProcess,
   virtual CRLSetFetcher* crl_set_fetcher() OVERRIDE;
   virtual BookmarkPromptController* bookmark_prompt_controller() OVERRIDE;
 
-  // content::NotificationObserver implementation.
-  virtual void Observe(int type,
-                       const content::NotificationSource& source,
-                       const content::NotificationDetails& details) OVERRIDE;
+  // PrefObserver implementation.
+  virtual void OnPreferenceChanged(PrefServiceBase* service,
+                                   const std::string& pref_name) OVERRIDE;
 
  private:
   void CreateMetricsService();