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

Source/modules/presentation/PresentationSession.cpp

Index: Source/modules/presentation/PresentationSession.cpp
diff --git a/Source/modules/presentation/PresentationSession.cpp b/Source/modules/presentation/PresentationSession.cpp
index a7920a0747f08f762c06e42e10cc656b282f16e3..03ac8d4cb0c029fe14854bc4e4bdaa7b1d9f7dd3 100644
--- a/Source/modules/presentation/PresentationSession.cpp
+++ b/Source/modules/presentation/PresentationSession.cpp
@@ -5,12 +5,20 @@
 #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 "public/platform/WebString.h"
+#include "public/platform/modules/presentation/WebPresentationSessionClient.h"
+#include "wtf/OwnPtr.h"
 
 namespace blink {
 
-PresentationSession::PresentationSession(ExecutionContext* executionContext)
-    : ContextLifecycleObserver(executionContext)
+PresentationSession::PresentationSession(LocalFrame* frame, const WebString& id)
+    : DOMWindowProperty(frame)
+    , m_id(id)
+    , m_state("disconnected")
 {
 }
 
@@ -19,9 +27,21 @@ PresentationSession::~PresentationSession()
 }
 
 // static
-PresentationSession* PresentationSession::create(ExecutionContext* executionContext)
+PresentationSession* PresentationSession::take(WebPresentationSessionClient* clientRaw, Presentation* presentation)
 {
-    return new PresentationSession(executionContext);
+    ASSERT(clientRaw);
+    ASSERT(presentation);
+    OwnPtr<WebPresentationSessionClient> client = adoptPtr(clientRaw);
+
+    PresentationSession* session = new PresentationSession(presentation->frame(), client->getId());
+    presentation->registerSession(session);
+    return session;
+}
+
+// static
+void PresentationSession::dispose(WebPresentationSessionClient* client)
+{
+    delete client;
 }
 
 const AtomicString& PresentationSession::interfaceName() const
@@ -31,13 +51,14 @@ const AtomicString& PresentationSession::interfaceName() const
 
 ExecutionContext* PresentationSession::executionContext() const
 {
-    return ContextLifecycleObserver::executionContext();
-}
+    if (!frame())
+        return nullptr;
+    return frame()->document();}
 
 DEFINE_TRACE(PresentationSession)
 {
     RefCountedGarbageCollectedEventTargetWithInlineData<PresentationSession>::trace(visitor);
-    ContextLifecycleObserver::trace(visitor);
+    DOMWindowProperty::trace(visitor);
 }
 
 void PresentationSession::postMessage(const String& message)