content: convert zoom notifications to observer usage

chrome/browser/profiles/off_the_record_profile_impl.h

Index: chrome/browser/profiles/off_the_record_profile_impl.h
diff --git a/chrome/browser/profiles/off_the_record_profile_impl.h b/chrome/browser/profiles/off_the_record_profile_impl.h
index 0da387471948fbbeb34673d42026aca56bce148b..4ce18eaf6ba69101ea002c7489ecbbf1f06ebbaa 100644
--- a/chrome/browser/profiles/off_the_record_profile_impl.h
+++ b/chrome/browser/profiles/off_the_record_profile_impl.h
@@ -11,8 +11,7 @@
 #include "chrome/browser/profiles/off_the_record_profile_io_data.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/ui/browser_list.h"
-#include "content/public/browser/notification_observer.h"
-#include "content/public/browser/notification_registrar.h"
+#include "content/public/browser/host_zoom_map.h"
 
 using base::Time;
 using base::TimeDelta;
@@ -27,7 +26,7 @@ using base::TimeDelta;
 //
 ////////////////////////////////////////////////////////////////////////////////
 class OffTheRecordProfileImpl : public Profile,
-                                public content::NotificationObserver {
+                                public content::HostZoomMap::Observer {
  public:
   explicit OffTheRecordProfileImpl(Profile* real_profile);
   virtual ~OffTheRecordProfileImpl();
@@ -105,10 +104,8 @@ class OffTheRecordProfileImpl : public Profile,
       GetSpeechRecognitionPreferences() OVERRIDE;
   virtual quota::SpecialStoragePolicy* GetSpecialStoragePolicy() OVERRIDE;
 
-  // content::NotificationObserver implementation.
-  virtual void Observe(int type,
-                       const content::NotificationSource& source,
-                       const content::NotificationDetails& details) OVERRIDE;
+  // content::HostZoomMap::Observer implementation:
+  virtual void OnZoomLevelChanged(const std::string& host) OVERRIDE;
 
  private:
   FRIEND_TEST_ALL_PREFIXES(OffTheRecordProfileImplTest, GetHostZoomMap);
@@ -121,8 +118,6 @@ class OffTheRecordProfileImpl : public Profile,
   virtual base::Callback<ChromeURLDataManagerBackend*(void)>
       GetChromeURLDataManagerBackendGetter() const OVERRIDE;
 
-  content::NotificationRegistrar registrar_;
-
   // The real underlying profile.
   Profile* profile_;