PushRegistration.unregister() can fail with a NetworkError.

Source/modules/push_messaging/PushRegistration.cpp

 // 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.
 
 #include "config.h"
 #include "modules/push_messaging/PushRegistration.h"
 
 #include "bindings/core/v8/CallbackPromiseAdapter.h"
 #include "bindings/core/v8/ScriptPromiseResolver.h"
+#include "modules/push_messaging/PushError.h"
 #include "modules/serviceworkers/ServiceWorkerRegistration.h"
 #include "public/platform/Platform.h"
 #include "public/platform/WebPushProvider.h"
 #include "public/platform/WebPushRegistration.h"
 #include "wtf/OwnPtr.h"
 
 namespace blink {
 
 PushRegistration* PushRegistration::take(ScriptPromiseResolver*, WebPushRegistration* pushRegistration, ServiceWorkerRegistration* serviceWorkerRegistration)
 {
@@ skipping 18 matching lines @@
 }
 
 ScriptPromise PushRegistration::unregister(ScriptState* scriptState)
 {
     RefPtr<ScriptPromiseResolver> resolver = ScriptPromiseResolver::create(scriptState);
     ScriptPromise promise = resolver->promise();
 
     WebPushProvider* webPushProvider = Platform::current()->pushProvider();
     ASSERT(webPushProvider);
 
-    webPushProvider->unregister(m_serviceWorkerRegistration->webRegistration(), new CallbackPromiseAdapter<bool, void>(resolver));
+    webPushProvider->unregister(m_serviceWorkerRegistration->webRegistration(), new CallbackPromiseAdapter<bool, PushError>(resolver));
     return promise;
 }
 
 void PushRegistration::trace(Visitor* visitor)
 {
     visitor->trace(m_serviceWorkerRegistration);
 }
 
 } // namespace blink