Remove support for PushSubscription.subscriptionId.

Source/modules/push_messaging/PushSubscription.h

 // Copyright 2014 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.
 
 #ifndef PushSubscription_h
 #define PushSubscription_h
 
 #include "bindings/core/v8/ScriptPromise.h"
 #include "bindings/core/v8/ScriptValue.h"
 #include "bindings/core/v8/ScriptWrappable.h"
 #include "platform/heap/Handle.h"
-#include "wtf/text/WTFString.h"
+#include "platform/weborigin/KURL.h"
 
 namespace blink {
 
 class ServiceWorkerRegistration;
 class ScriptPromiseResolver;
 class ScriptState;
 struct WebPushSubscription;
 
 class PushSubscription final : public GarbageCollectedFinalized<PushSubscription>, public ScriptWrappable {
     DEFINE_WRAPPERTYPEINFO();
 public:
     static PushSubscription* take(ScriptPromiseResolver*, WebPushSubscription*, ServiceWorkerRegistration*);
     static void dispose(WebPushSubscription* subscriptionRaw);
 
     virtual ~PushSubscription();
 
-    String endpoint() const;
-    const String& subscriptionId() const { return m_subscriptionId; }
+    KURL endpoint() const;
     ScriptPromise unsubscribe(ScriptState*);
 
     ScriptValue toJSONForBinding(ScriptState*);
 
     DECLARE_TRACE();
 
 private:
-    PushSubscription(const String& endpoint, const String& subscriptionId, ServiceWorkerRegistration*);
+    PushSubscription(const KURL& endpoint, ServiceWorkerRegistration*);
 
-    String m_endpoint;
-    String m_subscriptionId;
+    KURL m_endpoint;
     Member<ServiceWorkerRegistration> m_serviceWorkerRegistration;
 };
 
 } // namespace blink
 
 #endif // PushSubscription_h