Added plumbing for the availablechange event from Blink to WebPresentationClient.

Source/modules/presentation/NavigatorPresentation.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/NavigatorPresentation.h"
 
 #include "core/dom/Document.h"
 #include "core/frame/LocalFrame.h"
 #include "core/frame/Navigator.h"
 #include "modules/presentation/Presentation.h"
 #include "platform/heap/Handle.h"
 
 namespace blink {
 
-NavigatorPresentation::NavigatorPresentation(LocalFrame* frame)
-    : DOMWindowProperty(frame)
+NavigatorPresentation::NavigatorPresentation()
 {
 }
 
 NavigatorPresentation::~NavigatorPresentation()
 {
 }
 
 // static
 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());
+        supplement = new NavigatorPresentation();
         provideTo(navigator, supplementName(), adoptPtrWillBeNoop(supplement));
     }
     return *supplement;
 }
 
 // static
 Presentation* NavigatorPresentation::presentation(Navigator& navigator)
 {
-    return NavigatorPresentation::from(navigator).presentation();
-}
-
-Presentation* NavigatorPresentation::presentation()
-{
-    if (!m_presentation) {
-        if (!frame())
-            return 0;
-        m_presentation = Presentation::create(frame()->document());
+    NavigatorPresentation& self = NavigatorPresentation::from(navigator);
+    if (!self.m_presentation) {
+        if (!navigator.frame())
+            return nullptr;
+        self.m_presentation = Presentation::create(navigator.frame());
     }
-    return m_presentation.get();
+    return self.m_presentation.get();
 }
 
 void NavigatorPresentation::trace(Visitor* visitor)
 {
     visitor->trace(m_presentation);
     WillBeHeapSupplement<Navigator>::trace(visitor);
-    DOMWindowProperty::trace(visitor);
 }
 
 } // namespace blink