Refactor BeforeInstallPromptEvent to use ScriptPromiseProperty

Source/modules/app_banner/AppBannerCallbacks.cpp

+// 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.
+
+#include "config.h"
+#include "modules/app_banner/AppBannerCallbacks.h"
+
+#include "modules/app_banner/BeforeInstallPromptEvent.h"
+
+namespace blink {
+
+AppBannerCallbacks::AppBannerCallbacks(BeforeInstallPromptEvent* event)
+    : m_event(event)
+{
+}
+
+void AppBannerCallbacks::onSuccess(WebAppBannerPromptResult* result)
+{
+    OwnPtr<WebAppBannerPromptResult> ownPtr = adoptPtr(result);
+    m_event->resolveUserChoice(AppBannerPromptResult::take(ownPtr.release()));
+}
+
+} // namespace blink