[PresentationAPI] Plumbing |onstatechange| event for the PresentationSession from Blink to platform/

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 0e470d6bc75f570accdb7035c48c0620ce362e4e..4c6ddaebe1a6e9815b73600a290024e1a6cec557 100644
--- a/Source/modules/presentation/Presentation.cpp
+++ b/Source/modules/presentation/Presentation.cpp
@@ -17,6 +17,7 @@
 #include "modules/presentation/DefaultSessionStartEvent.h"
 #include "modules/presentation/PresentationController.h"
 #include "modules/presentation/PresentationSessionClientCallbacks.h"
+#include "public/platform/modules/presentation/WebPresentationSessionClient.h"
 
 namespace blink {
 
@@ -151,6 +152,15 @@ void Presentation::didStartDefaultSession(PresentationSession* session)
     dispatchEvent(DefaultSessionStartEvent::create(EventTypeNames::defaultsessionstart, session));
 }
 
+void Presentation::didChangeSessionState(WebPresentationSessionClient* sessionClient, WebPresentationSessionState sessionState)
+{
+    PresentationSession* session = findSession(sessionClient);
+    if (session)
+        session->didChangeState(sessionState);
+
+    PresentationSession::dispose(sessionClient);
+}
+
 void Presentation::registerSession(PresentationSession* session)
 {
     m_openSessions.add(session);
@@ -163,4 +173,13 @@ PresentationController* Presentation::presentationController()
     return PresentationController::from(*frame());
 }
 
+PresentationSession* Presentation::findSession(WebPresentationSessionClient* sessionClient)
+{
+    for (const auto& session : m_openSessions) {
+        if (session->matches(sessionClient))
+            return session.get();
+    }
+    return nullptr;
+}
+
 } // namespace blink