Push API: rename registration to subscription.

Source/modules/push_messaging/PushSubscription.idl

Index: Source/modules/push_messaging/PushSubscription.idl
diff --git a/Source/modules/push_messaging/PushRegistration.idl b/Source/modules/push_messaging/PushSubscription.idl
similarity index 44%
rename from Source/modules/push_messaging/PushRegistration.idl
rename to Source/modules/push_messaging/PushSubscription.idl
index 243215d9fc20fb200d414d64097ca52d7a21f3df..81451a4bdfb68ca59de6cde339dda5b2e0add7b7 100644
--- a/Source/modules/push_messaging/PushRegistration.idl
+++ b/Source/modules/push_messaging/PushSubscription.idl
@@ -1,14 +1,14 @@
-// Copyright 2014 The Chromium Authors. All rights reserved.
+// Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// http://www.w3.org/TR/push-api/#pushregistration-interface
+// http://w3c.github.io/push-api/#pushsubscription-interface
 
 [
     GarbageCollected,
     RuntimeEnabled=PushMessaging,
-] interface PushRegistration {
+] interface PushSubscription {
     readonly attribute DOMString endpoint;
-    readonly attribute DOMString registrationId;
-    [CallWith=ScriptState] Promise<boolean> unregister();
+    readonly attribute DOMString subscriptionId;
+    [CallWith=ScriptState] Promise<boolean> unsubscribe();
 };