Cleanup/ Remove deprecated extension notification from ExtensionHost

chrome/browser/extensions/extension_view_host.h

Index: chrome/browser/extensions/extension_view_host.h
diff --git a/chrome/browser/extensions/extension_view_host.h b/chrome/browser/extensions/extension_view_host.h
index 63cb61e1de847d23e27e2574666936b0cb405de7..861d6be9cd75be74eea7a8c990441fe7ac70914e 100644
--- a/chrome/browser/extensions/extension_view_host.h
+++ b/chrome/browser/extensions/extension_view_host.h
@@ -9,6 +9,8 @@
 #include "components/web_modal/popup_manager.h"
 #include "components/web_modal/web_contents_modal_dialog_host.h"
 #include "components/web_modal/web_contents_modal_dialog_manager_delegate.h"
+#include "content/public/browser/notification_observer.h"
+#include "content/public/browser/notification_registrar.h"
 #include "extensions/browser/extension_host.h"
 
 class Browser;
@@ -29,7 +31,8 @@ class ExtensionView;
 class ExtensionViewHost
     : public ExtensionHost,
       public web_modal::WebContentsModalDialogManagerDelegate,
-      public web_modal::WebContentsModalDialogHost {
+      public web_modal::WebContentsModalDialogHost,
+      public content::NotificationObserver {
  public:
   ExtensionViewHost(const Extension* extension,
                     content::SiteInstance* site_instance,
@@ -127,6 +130,8 @@ class ExtensionViewHost
   // a parent window.
   scoped_ptr<web_modal::PopupManager> popup_manager_;
 
+  content::NotificationRegistrar registrar_;
+
   DISALLOW_COPY_AND_ASSIGN(ExtensionViewHost);
 };