Remove content::NotificationObserver dependency from most Prefs code.

chrome/browser/plugins/plugin_prefs.h

Index: chrome/browser/plugins/plugin_prefs.h
diff --git a/chrome/browser/plugins/plugin_prefs.h b/chrome/browser/plugins/plugin_prefs.h
index 95fe301c381435018bc4b2a80ec21fbee9f936d0..594e3d3d2709f235ef68f94c2cb4345c1c9f6114 100644
--- a/chrome/browser/plugins/plugin_prefs.h
+++ b/chrome/browser/plugins/plugin_prefs.h
@@ -12,11 +12,11 @@
 #include "base/basictypes.h"
 #include "base/file_path.h"
 #include "base/prefs/public/pref_change_registrar.h"
+#include "base/prefs/public/pref_observer.h"
 #include "base/synchronization/lock.h"
 #include "chrome/browser/plugins/plugin_finder.h"
 #include "chrome/browser/prefs/pref_service.h"
 #include "chrome/browser/profiles/refcounted_profile_keyed_service.h"
-#include "content/public/browser/notification_observer.h"
 
 class Profile;
 
@@ -35,7 +35,7 @@ class PluginList;
 // enabled or disabled.
 // Except where otherwise noted, it can be used on every thread.
 class PluginPrefs : public RefcountedProfileKeyedService,
-                    public content::NotificationObserver {
+                    public PrefObserver {
  public:
   enum PolicyStatus {
     NO_POLICY = 0,  // Neither enabled or disabled by policy.
@@ -85,10 +85,9 @@ class PluginPrefs : public RefcountedProfileKeyedService,
   // RefCountedProfileKeyedBase method override.
   virtual void ShutdownOnUIThread() OVERRIDE;
 
-  // content::NotificationObserver method override.
-  virtual void Observe(int type,
-                       const content::NotificationSource& source,
-                       const content::NotificationDetails& details) OVERRIDE;
+  // PrefObserver method override.
+  virtual void OnPreferenceChanged(PrefServiceBase* service,
+                                   const std::string& pref_name) OVERRIDE;
 
  private:
   friend class base::RefCountedThreadSafe<PluginPrefs>;