content: convert zoom notifications to observer usage

chrome/browser/ui/zoom/zoom_controller.h

Index: chrome/browser/ui/zoom/zoom_controller.h
diff --git a/chrome/browser/ui/zoom/zoom_controller.h b/chrome/browser/ui/zoom/zoom_controller.h
index 1dd7809c84c59acb7ebbfbf7f5bb0bf95d1ff318..2dda110d2df2277577eb48c78d882ba1cb175996 100644
--- a/chrome/browser/ui/zoom/zoom_controller.h
+++ b/chrome/browser/ui/zoom/zoom_controller.h
@@ -8,8 +8,7 @@
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "base/prefs/public/pref_member.h"
-#include "content/public/browser/notification_observer.h"
-#include "content/public/browser/notification_registrar.h"
+#include "content/public/browser/host_zoom_map.h"
 #include "content/public/browser/web_contents_observer.h"
 #include "content/public/browser/web_contents_user_data.h"
 
@@ -20,8 +19,7 @@ class WebContents;
 }
 
 // Per-tab class to manage the Omnibox zoom icon.
-class ZoomController : public content::NotificationObserver,
-                       public content::WebContentsObserver,
+class ZoomController : public content::WebContentsObserver,
                        public content::WebContentsUserData<ZoomController> {
  public:
   virtual ~ZoomController();
@@ -41,16 +39,13 @@ class ZoomController : public content::NotificationObserver,
       const content::LoadCommittedDetails& details,
       const content::FrameNavigateParams& params) OVERRIDE;
 
-  // content::NotificationObserver overrides:
-  virtual void Observe(int type,
-                       const content::NotificationSource& source,
-                       const content::NotificationDetails& details) OVERRIDE;
-
  private:
   explicit ZoomController(content::WebContents* web_contents);
   friend class content::WebContentsUserData<ZoomController>;
   friend class ZoomControllerTest;
 
+  void OnZoomLevelChanged(const std::string& host);
+
   // Updates the zoom icon and zoom percentage based on current values and
   // notifies the observer if changes have occurred. |host| may be empty,
   // meaning the change should apply to ~all sites. If it is not empty, the
@@ -60,14 +55,16 @@ class ZoomController : public content::NotificationObserver,
   // The current zoom percentage.
   int zoom_percent_;
 
-  content::NotificationRegistrar registrar_;
-
   // Used to access the default zoom level preference.
   DoublePrefMember default_zoom_level_;
 
   // Observer receiving notifications on state changes.
   ZoomObserver* observer_;
 
+  content::BrowserContext* browser_context_;
+
+  content::HostZoomMap::ZoomLevelChangedCallback zoom_callback_;
+
   DISALLOW_COPY_AND_ASSIGN(ZoomController);
 };