Add the Presentation API module and a single event target

Source/modules/presentation/NavigatorPresentation.cpp

+/*
+ *  Copyright (C) 2014 Google Inc.

[Peter Beverloo, 2014/07/19 10:16:12]

nit: Need to use the new copyright comment (as in the header file).

[whywhat, 2014/07/23 00:39:25]

Done.

+ *
+ *  This library is free software; you can redistribute it and/or
+ *  modify it under the terms of the GNU Lesser General Public
+ *  License as published by the Free Software Foundation; either
+ *  version 2 of the License, or (at your option) any later version.
+ *
+ *  This library is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ *  Lesser General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Lesser General Public
+ *  License along with this library; if not, write to the Free Software
+ *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+
+#include "config.h"
+#include "modules/presentation/NavigatorPresentation.h"
+
+#include "core/dom/Document.h"
+#include "core/frame/LocalFrame.h"
+#include "core/frame/Navigator.h"
+#include "modules/presentation/Presentation.h"
+
+namespace WebCore {
+
+NavigatorPresentation::NavigatorPresentation(LocalFrame* frame)
+    : DOMWindowProperty(frame)
+{
+}
+
+NavigatorPresentation::~NavigatorPresentation()
+{
+}
+
+// static

[Peter Beverloo, 2014/07/19 10:16:12]

micro nit: The // static comments aren't part of the Blink styleguide. Not
harmful either, though.

[whywhat, 2014/07/23 00:39:25]

Acknowledged.

+const char* NavigatorPresentation::supplementName()
+{
+    return "NavigatorPresentation";
+}
+
+// static
+NavigatorPresentation& NavigatorPresentation::from(Navigator& navigator)
+{
+    NavigatorPresentation* supplement = static_cast<NavigatorPresentation*>(WillBeHeapSupplement<Navigator>::from(navigator, supplementName()));
+    if (!supplement) {
+        supplement = new NavigatorPresentation(navigator.frame());
+        provideTo(navigator, supplementName(), adoptPtrWillBeNoop(supplement));
+    }
+    return *supplement;
+}
+
+// static
+Presentation* NavigatorPresentation::presentation(Navigator& navigator)

[Peter Beverloo, 2014/07/19 10:16:12]

You should return a reference since this won't ever be NULL.

[whywhat, 2014/07/23 00:39:25]

Done. I wonder if it should be NULL in cases when the device doesn't support
effective mirroring to a remote agent or second screen though (e.g. cheap phones
that can't share screen with Chromecasts or connect to anything via a microUSB
to HDMI cable). 

[Peter Beverloo, 2014/07/25 18:01:17]

Sounds like something you should have a design document for.

+{
+    return NavigatorPresentation::from(navigator).presentation();
+}
+
+Presentation* NavigatorPresentation::presentation() const
+{
+    if (!m_presentation && frame())

[Peter Beverloo, 2014/07/19 10:16:12]

ASSERT() on frame() instead? When wouldn't there be a frame?

[whywhat, 2014/07/23 00:39:25]

No idea. Seems everyone's checking for it :)

+        m_presentation = Presentation::create(frame()->document());
+    return m_presentation.get();
+}
+
+void NavigatorPresentation::trace(Visitor* visitor)
+{
+    visitor->trace(m_presentation);
+    WillBeHeapSupplement<Navigator>::trace(visitor);
+}
+
+} // namespace WebCore