Use ExtensionRegistryObserver instead of deprecated extension notification from c/b/e/api.

chrome/browser/extensions/api/push_messaging/push_messaging_api.h

Index: chrome/browser/extensions/api/push_messaging/push_messaging_api.h
diff --git a/chrome/browser/extensions/api/push_messaging/push_messaging_api.h b/chrome/browser/extensions/api/push_messaging/push_messaging_api.h
index 0b5884b92cc4cfbca6db2a39ba0b1afcfb89facb..7ea8b6b3e4cc75441a331cb8a6bf41326eb6e0ab 100644
--- a/chrome/browser/extensions/api/push_messaging/push_messaging_api.h
+++ b/chrome/browser/extensions/api/push_messaging/push_messaging_api.h
@@ -11,6 +11,7 @@
 #include "base/compiler_specific.h"
 #include "base/gtest_prod_util.h"
 #include "base/memory/scoped_ptr.h"
+#include "base/scoped_observer.h"
 #include "chrome/browser/extensions/api/push_messaging/obfuscated_gaia_id_fetcher.h"
 #include "chrome/browser/extensions/api/push_messaging/push_messaging_invalidation_handler_delegate.h"
 #include "chrome/browser/extensions/chrome_extension_function.h"
@@ -18,6 +19,7 @@
 #include "content/public/browser/notification_observer.h"
 #include "content/public/browser/notification_registrar.h"
 #include "extensions/browser/browser_context_keyed_api_factory.h"
+#include "extensions/browser/extension_registry_observer.h"
 #include "google_apis/gaia/google_service_auth_error.h"
 #include "google_apis/gaia/oauth2_token_service.h"
 
@@ -28,7 +30,7 @@ class BrowserContext;
 }
 
 namespace extensions {
-
+class ExtensionRegistry;
 class PushMessagingInvalidationMapper;
 
 // Observes a single InvalidationHandler and generates onMessage events.
@@ -109,7 +111,8 @@ class PushMessagingGetChannelIdFunction
 };
 
 class PushMessagingAPI : public BrowserContextKeyedAPI,
-                         public content::NotificationObserver {
+                         public content::NotificationObserver,
+                         public ExtensionRegistryObserver {
  public:
   explicit PushMessagingAPI(content::BrowserContext* context);
   virtual ~PushMessagingAPI();
@@ -146,6 +149,14 @@ class PushMessagingAPI : public BrowserContextKeyedAPI,
                        const content::NotificationSource& source,
                        const content::NotificationDetails& details) OVERRIDE;
 
+  // Overridden from ExtensionRegistryObserver.
+  virtual void OnExtensionLoaded(content::BrowserContext* browser_context,
+                                 const Extension* extension) OVERRIDE;
+  virtual void OnExtensionUnloaded(
+      content::BrowserContext* browser_context,
+      const Extension* extension,
+      UnloadedExtensionInfo::Reason reason) OVERRIDE;
+
   // Created lazily when an app or extension with the push messaging permission
   // is loaded.
   scoped_ptr<PushMessagingEventRouter> event_router_;
@@ -153,6 +164,10 @@ class PushMessagingAPI : public BrowserContextKeyedAPI,
 
   content::NotificationRegistrar registrar_;
 
+  // Listen to extension load, unload notifications.
+  ScopedObserver<ExtensionRegistry, ExtensionRegistryObserver>
+      extension_registry_observer_;
+
   Profile* profile_;
 
   DISALLOW_COPY_AND_ASSIGN(PushMessagingAPI);