Add the Presentation API module and a single event target

Source/modules/presentation/Presentation.h

+// 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.
+
+#ifndef Presentation_h
+#define Presentation_h
+
+#include "bindings/core/v8/ScriptWrappable.h"
+#include "core/events/EventTarget.h"
+#include "core/frame/DOMWindowProperty.h"
+
+namespace blink {
+
+class Presentation FINAL
+    : public GarbageCollectedFinalized<Presentation>
+    , public EventTargetWithInlineData
+    , DOMWindowProperty {

[Peter Beverloo, 2014/07/25 18:01:18]

This shouldn't be a DOMWindowProperty, definitely not one without a visibility
keyword :-).

In order to support the EventTarget implementation, you need access to the
execution context.

Looking to the near future, I guess you will need to tell the embedder when to
start and stop listening to changes in active devices. For that you would extend
from ContextLifecycleObserver, or from ActiveDOMObject if there's a pending
operation to keep the object alive.

Extending from CLO seems fine for now. If you don't want to do that, you could
keep the execution context as a weak member (RawPtrWillBeWeakMember).

[whywhat, 2014/08/19 18:07:35]

Done.

+    DEFINE_EVENT_TARGET_REFCOUNTING(EventTargetWithInlineData);
+public:
+    static Presentation* create(LocalFrame*);
+    virtual ~Presentation();
+
+    // EventTarget implementation.
+    virtual const WTF::AtomicString& interfaceName() const OVERRIDE;
+    virtual ExecutionContext* executionContext() const OVERRIDE;
+
+    virtual void trace(Visitor*) OVERRIDE;
+
+    bool displayAvailable() const;
+
+    DEFINE_ATTRIBUTE_EVENT_LISTENER(availablechange);
+
+private:
+    explicit Presentation(LocalFrame*);
+};
+
+} // namespace blink
+
+#endif // Presentation_h