[AppBanner] Blink implementation of an event when an install banner is shown.

Source/modules/app_banner/BeforeInstallPromptEvent.cpp

Index: Source/modules/app_banner/BeforeInstallPromptEvent.cpp
diff --git a/Source/modules/app_banner/BeforeInstallPromptEvent.cpp b/Source/modules/app_banner/BeforeInstallPromptEvent.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..47f5b7739b21a376f2f9a25cb723dd4bf9534b84
--- /dev/null
+++ b/Source/modules/app_banner/BeforeInstallPromptEvent.cpp
@@ -0,0 +1,50 @@
+// 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/BeforeInstallPromptEvent.h"
+
+#include "bindings/core/v8/ScriptPromise.h"
+#include "core/dom/DOMException.h"
+#include "core/dom/ExceptionCode.h"
+#include "modules/app_banner/BeforeInstallPromptEventInit.h"
+
+namespace blink {
+
+BeforeInstallPromptEvent::BeforeInstallPromptEvent()
+{
+}
+
+BeforeInstallPromptEvent::BeforeInstallPromptEvent(const AtomicString& name, const String& platform)
+    : Event(name, false, true)
+    , m_platform(platform)
+{
+}
+
+BeforeInstallPromptEvent::BeforeInstallPromptEvent(const AtomicString& name, const BeforeInstallPromptEventInit& init)
+    : Event(name, false, true)
+    , m_platform(init.platform())
+{
+}
+
+BeforeInstallPromptEvent::~BeforeInstallPromptEvent()
+{
+}
+
+String BeforeInstallPromptEvent::platform() const
+{
+    return m_platform;
+}
+
+ScriptPromise BeforeInstallPromptEvent::userChoice(ScriptState* scriptState) const
+{
+    return ScriptPromise::rejectWithDOMException(scriptState, DOMException::create(NotSupportedError, "Subscription failed - no active Service Worker"));
+}
+
+const AtomicString& BeforeInstallPromptEvent::interfaceName() const
+{
+    return EventNames::BeforeInstallPromptEvent;
+}
+
+} // namespace blink