[PresentationAPI] Added plumbing for start/joinSession from JS to platform

Source/modules/presentation/PresentationSession.h

Index: Source/modules/presentation/PresentationSession.h
diff --git a/Source/modules/presentation/PresentationSession.h b/Source/modules/presentation/PresentationSession.h
index d2116156c7213333d20044e7b1984041b2069b4c..b6b74178f703b5c27c4dea050ac8ccbece64e4ae 100644
--- a/Source/modules/presentation/PresentationSession.h
+++ b/Source/modules/presentation/PresentationSession.h
@@ -5,21 +5,23 @@
 #ifndef PresentationSession_h
 #define PresentationSession_h
 
-#include "core/dom/ContextLifecycleObserver.h"
 #include "core/events/EventTarget.h"
+#include "core/frame/DOMWindowProperty.h"
 #include "wtf/text/AtomicString.h"
 #include "wtf/text/WTFString.h"
 
 namespace blink {
 
+class WebPresentationSessionClient;
+
 class PresentationSession final
     : public RefCountedGarbageCollectedEventTargetWithInlineData<PresentationSession>
-    , public ContextLifecycleObserver {
+    , public DOMWindowProperty {
     DEFINE_EVENT_TARGET_REFCOUNTING_WILL_BE_REMOVED(RefCountedGarbageCollected<PresentationSession>);
     WILL_BE_USING_GARBAGE_COLLECTED_MIXIN(PresentationSession);
     DEFINE_WRAPPERTYPEINFO();
 public:
-    static PresentationSession* create(ExecutionContext*);
+    static PresentationSession* create(LocalFrame*, WebPresentationSessionClient*);
     virtual ~PresentationSession();
 
     // EventTarget implementation.
@@ -38,7 +40,7 @@ public:
     DEFINE_ATTRIBUTE_EVENT_LISTENER(statechange);
 
 private:
-    explicit PresentationSession(ExecutionContext*);
+    PresentationSession(LocalFrame*, WebPresentationSessionClient*);
 
     String m_id;
     AtomicString m_state;