Remove support for PushSubscription.subscriptionId.

Source/modules/push_messaging/PushSubscription.h

Index: Source/modules/push_messaging/PushSubscription.h
diff --git a/Source/modules/push_messaging/PushSubscription.h b/Source/modules/push_messaging/PushSubscription.h
index 8dbfd21350ba28cec11695c90fa50a232bbb49f7..e5a6305cfdc9dc9c89d8b4aacf7e4e15f4e10a83 100644
--- a/Source/modules/push_messaging/PushSubscription.h
+++ b/Source/modules/push_messaging/PushSubscription.h
@@ -9,7 +9,7 @@
 #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 {
 
@@ -26,8 +26,7 @@ public:
 
     virtual ~PushSubscription();
 
-    String endpoint() const;
-    const String& subscriptionId() const { return m_subscriptionId; }
+    KURL endpoint() const;
     ScriptPromise unsubscribe(ScriptState*);
 
     ScriptValue toJSONForBinding(ScriptState*);
@@ -35,10 +34,9 @@ public:
     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;
 };