[Presentation API] Added the DefaultPresentationStart event and parsing of the default presentation…

Source/modules/presentation/Presentation.cpp

Index: Source/modules/presentation/Presentation.cpp
diff --git a/Source/modules/presentation/Presentation.cpp b/Source/modules/presentation/Presentation.cpp
index 6213d4f13505572dec88ee06057941372f2fe0df..0e470d6bc75f570accdb7035c48c0620ce362e4e 100644
--- a/Source/modules/presentation/Presentation.cpp
+++ b/Source/modules/presentation/Presentation.cpp
@@ -14,6 +14,7 @@
 #include "core/frame/LocalFrame.h"
 #include "modules/EventTargetModules.h"
 #include "modules/presentation/AvailableChangeEvent.h"
+#include "modules/presentation/DefaultSessionStartEvent.h"
 #include "modules/presentation/PresentationController.h"
 #include "modules/presentation/PresentationSessionClientCallbacks.h"
 
@@ -145,6 +146,11 @@ bool Presentation::isAvailableChangeWatched() const
     return hasEventListeners(EventTypeNames::availablechange);
 }
 
+void Presentation::didStartDefaultSession(PresentationSession* session)
+{
+    dispatchEvent(DefaultSessionStartEvent::create(EventTypeNames::defaultsessionstart, session));
+}
+
 void Presentation::registerSession(PresentationSession* session)
 {
     m_openSessions.add(session);