Add a SupervisedUserServiceObserver.

chrome/browser/supervised_user/supervised_user_interstitial.h

Index: chrome/browser/supervised_user/supervised_user_interstitial.h
diff --git a/chrome/browser/supervised_user/supervised_user_interstitial.h b/chrome/browser/supervised_user/supervised_user_interstitial.h
index 29f3d7226c6d7eb377fbf00ac10d8c872ee79d87..90806e70ff32eb0607be2b54d6a1cd178e5010f7 100644
--- a/chrome/browser/supervised_user/supervised_user_interstitial.h
+++ b/chrome/browser/supervised_user/supervised_user_interstitial.h
@@ -8,7 +8,7 @@
 #include <string>
 
 #include "base/callback.h"
-#include "base/prefs/pref_change_registrar.h"
+#include "chrome/browser/supervised_user/supervised_user_service_observer.h"
 #include "content/public/browser/interstitial_page_delegate.h"
 #include "url/gurl.h"
 
@@ -20,7 +20,8 @@ class WebContents;
 // Delegate for an interstitial page when a page is blocked for a supervised
 // user because it is on a blacklist (in "allow everything" mode) or not on any
 // whitelist (in "allow only specified sites" mode).
-class SupervisedUserInterstitial : public content::InterstitialPageDelegate {
+class SupervisedUserInterstitial : public content::InterstitialPageDelegate,
+                                   public SupervisedUserServiceObserver {
  public:
   static void Show(content::WebContents* web_contents,
                    const GURL& url,
@@ -40,12 +41,14 @@ class SupervisedUserInterstitial : public content::InterstitialPageDelegate {
   virtual void OnProceed() OVERRIDE;
   virtual void OnDontProceed() OVERRIDE;
 
+  // SupervisedUserServiceObserver implementation.
+  virtual void OnURLFilterChanged() OVERRIDE;
+
   // Returns whether the blocked URL is now allowed. Called initially before the
   // interstitial is shown (to catch race conditions), or when the URL filtering
   // prefs change.
   bool ShouldProceed();
 
-  void OnFilteringPrefsChanged();
   void DispatchContinueRequest(bool continue_request);
 
   // Owns the interstitial, which owns us.
@@ -53,8 +56,6 @@ class SupervisedUserInterstitial : public content::InterstitialPageDelegate {
 
   content::InterstitialPage* interstitial_page_;  // Owns us.
 
-  PrefChangeRegistrar pref_change_registrar_;
-
   GURL url_;
 
   base::Callback<void(bool)> callback_;