Implement DragEvent and move MouseEvent.dataTransfer

Source/core/events/DragEvent.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 "core/events/DragEvent.h"
+
+#include "core/clipboard/DataTransfer.h"
+#include "core/dom/Element.h"
+#include "core/events/EventDispatcher.h"
+
+namespace blink {
+
+DragEvent::DragEvent()
+    : m_dataTransfer(nullptr)
+{
+}
+
+DragEvent::DragEvent(DataTransfer* dataTransfer)
+    : m_dataTransfer(dataTransfer)
+{
+}
+
+DragEvent::DragEvent(const AtomicString& type, const DragEventInit& initializer)
+    : MouseEvent(type, initializer)
+    , m_dataTransfer(initializer.dataTransfer())
+{
+}
+
+DEFINE_TRACE(DragEvent)
+{
+    visitor->trace(m_dataTransfer);
+    MouseEvent::trace(visitor);
+}
+
+PassRefPtrWillBeRawPtr<DragEventDispatchMediator> DragEventDispatchMediator::create(PassRefPtrWillBeRawPtr<DragEvent> dragEvent)
+{
+    return adoptRefWillBeNoop(new DragEventDispatchMediator(dragEvent));
+}
+
+bool DragEvent::isDragEvent() const
+{
+    return true;
+}
+
+bool DragEvent::isMouseEvent() const

[Rick Byers, 2015/08/06 14:22:31]

Why do you want isMouseEvent to be true for DragEvents?  That's inconsistent
with how WheelEvent behaves (which is also a subclass of MouseEvent).  I think
we want to use the same pattern for all Event subclasses.  Can we update the
necessary callers instead of removing this?

[Jimmy Jo, 2015/08/07 02:42:02]

Done.

+{
+    return false;
+}
+
+DragEventDispatchMediator::DragEventDispatchMediator(PassRefPtrWillBeRawPtr<DragEvent> dragEvent)
+    : EventDispatchMediator(dragEvent)
+{
+}
+
+DragEvent& DragEventDispatchMediator::event() const
+{
+    return toDragEvent(EventDispatchMediator::event());
+}
+
+bool DragEventDispatchMediator::dispatchEvent(EventDispatcher& dispatcher) const
+{
+    event().eventPath().adjustForRelatedTarget(dispatcher.node(), event().relatedTarget());
+    return EventDispatchMediator::dispatchEvent(dispatcher);
+}
+
+} // namespace blink