Add the Blink APIs for the WebNotificationManager.

public/platform/Platform.h

Index: public/platform/Platform.h
diff --git a/public/platform/Platform.h b/public/platform/Platform.h
index c319e30c3ab10f33258b52f0ef4015c0d13169d6..618383000edc307fa8c66d15895d5270498287cf 100644
--- a/public/platform/Platform.h
+++ b/public/platform/Platform.h
@@ -85,7 +85,7 @@ class WebMediaStreamCenter;
 class WebMediaStreamCenterClient;
 class WebMessagePortChannel;
 class WebMimeRegistry;
-class WebNotificationPresenter;
+class WebNotificationManager;
 class WebPluginListBuilder;
 class WebPrescientNetworking;
 class WebPublicSuffixList;
@@ -632,7 +632,7 @@ public:
 
     // Web Notifications --------------------------------------------------
 
-    virtual WebNotificationPresenter* notificationPresenter() { return 0; }
+    virtual WebNotificationManager* notificationManager() { return 0; }
 
 
     // Geofencing ---------------------------------------------------------