[Presentation API] Adds close method to Presentation session.

Source/modules/presentation/PresentationSession.cpp

 // 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.
 
 #include "config.h"
 #include "modules/presentation/PresentationSession.h"
 
 #include "core/dom/Document.h"
 #include "core/frame/LocalFrame.h"
 #include "modules/EventTargetModules.h"
 #include "modules/presentation/Presentation.h"
+#include "modules/presentation/PresentationController.h"
 #include "public/platform/WebString.h"
 #include "public/platform/modules/presentation/WebPresentationSessionClient.h"
 #include "wtf/OwnPtr.h"
 
 namespace blink {
 
 PresentationSession::PresentationSession(LocalFrame* frame, const WebString& id)
     : DOMWindowProperty(frame)
     , m_id(id)
     , m_state("disconnected")
@@ skipping 38 matching lines @@
     RefCountedGarbageCollectedEventTargetWithInlineData<PresentationSession>::trace(visitor);
     DOMWindowProperty::trace(visitor);
 }
 
 void PresentationSession::postMessage(const String& message)
 {
 }
 
 void PresentationSession::close()
 {
+    PresentationController* controller = presentationController();
+    if (controller) {

[whywhat, 2015/03/17 23:35:19]

nit: remove the braces

[haibinlu, 2015/03/18 00:58:22]

Done.

+        controller->closeSession(m_id);
+    }
+}
+
+PresentationController* PresentationSession::presentationController()
+{
+    if (!frame())
+        return nullptr;
+    return PresentationController::from(*frame());
 }
 
 } // namespace blink