Remove content::NotificationObserver dependency from most Prefs code.

chrome/browser/net/net_pref_observer.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CHROME_BROWSER_NET_NET_PREF_OBSERVER_H_
 #define CHROME_BROWSER_NET_NET_PREF_OBSERVER_H_
 
 #include "base/basictypes.h"
+#include "base/prefs/public/pref_observer.h"
 #include "chrome/browser/api/prefs/pref_member.h"
-#include "content/public/browser/notification_observer.h"
 
 namespace chrome_browser_net {
 class Predictor;
 }
 
 namespace prerender {
 class PrerenderManager;
 }
 
 class PrefService;
 
 // Monitors network-related preferences for changes and applies them.
 // The supplied PrefService must outlive this NetPrefObserver.
 // Must be used only on the UI thread.
-class NetPrefObserver : public content::NotificationObserver {
+class NetPrefObserver : public PrefObserver {
  public:
   // |prefs| must be non-NULL and |*prefs| must outlive this.
   // |prerender_manager| may be NULL. If not, |*prerender_manager| must
   // outlive this.
   NetPrefObserver(PrefService* prefs,
                   prerender::PrerenderManager* prerender_manager,
                   chrome_browser_net::Predictor* predictor);
   virtual ~NetPrefObserver();
 
-  // content::NotificationObserver
-  virtual void Observe(int type,
-                       const content::NotificationSource& source,
-                       const content::NotificationDetails& details) OVERRIDE;
+  // PrefObserver
+  virtual void OnPreferenceChanged(PrefServiceBase* service,
+                                   const std::string& pref_name) OVERRIDE;
 
   static void RegisterPrefs(PrefService* prefs);
 
  private:
   void ApplySettings();
 
   BooleanPrefMember network_prediction_enabled_;
   BooleanPrefMember spdy_disabled_;
   prerender::PrerenderManager* prerender_manager_;
   chrome_browser_net::Predictor* predictor_;
 
   DISALLOW_COPY_AND_ASSIGN(NetPrefObserver);
 };
 
 #endif  // CHROME_BROWSER_NET_NET_PREF_OBSERVER_H_