[PresentationAPI] Plumbing |onstatechange| event for the PresentationSession from Blink 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 4727bebdb9c0397281ff4af261da66203d9597eb..47ba6253b3d33c471419808f6e6918b48f272bdd 100644
--- a/Source/modules/presentation/PresentationSession.cpp
+++ b/Source/modules/presentation/PresentationSession.cpp
@@ -6,21 +6,43 @@
 #include "modules/presentation/PresentationSession.h"
 
 #include "core/dom/Document.h"
+#include "core/events/Event.h"
 #include "core/frame/LocalFrame.h"
 #include "modules/EventTargetModules.h"
 #include "modules/presentation/Presentation.h"
 #include "modules/presentation/PresentationController.h"
-#include "public/platform/WebString.h"
 #include "public/platform/modules/presentation/WebPresentationSessionClient.h"
+#include "wtf/Assertions.h"
 #include "wtf/OwnPtr.h"
+#include "wtf/text/AtomicString.h"
 
 namespace blink {
 
-PresentationSession::PresentationSession(LocalFrame* frame, const WebString& id, const WebString& url)
+namespace {
+
+const AtomicString& SessionStateToString(WebPresentationSessionState state)
+{
+    DEFINE_STATIC_LOCAL(const AtomicString, connectedValue, ("connected", AtomicString::ConstructFromLiteral));
+    DEFINE_STATIC_LOCAL(const AtomicString, disconnectedValue, ("disconnected", AtomicString::ConstructFromLiteral));
+
+    switch (state) {
+    case WebPresentationSessionState::Connected:
+        return connectedValue;
+    case WebPresentationSessionState::Disconnected:
+        return disconnectedValue;
+    }
+
+    ASSERT_NOT_REACHED();
+    return disconnectedValue;
+}
+
+} // namespace
+
+PresentationSession::PresentationSession(LocalFrame* frame, const String& id, const String& url)
     : DOMWindowProperty(frame)
     , m_id(id)
     , m_url(url)
-    , m_state("disconnected")
+    , m_state(WebPresentationSessionState::Disconnected)
 {
 }
 
@@ -63,19 +85,38 @@ DEFINE_TRACE(PresentationSession)
     DOMWindowProperty::trace(visitor);
 }
 
+const AtomicString& PresentationSession::state() const
+{
+    return SessionStateToString(m_state);
+}
+
 void PresentationSession::postMessage(const String& message)
 {
 }
 
 void PresentationSession::close()
 {
-    if (m_state != "connected")
+    if (m_state != WebPresentationSessionState::Connected)
         return;
     PresentationController* controller = presentationController();
     if (controller)
         controller->closeSession(m_url, m_id);
 }
 
+bool PresentationSession::matches(WebPresentationSessionClient* client) const
+{
+    return client && m_url == static_cast<String>(client->getUrl()) && m_id == static_cast<String>(client->getId());
+}
+
+void PresentationSession::didChangeState(WebPresentationSessionState state)
+{
+    if (m_state == state)
+        return;
+
+    m_state = state;
+    dispatchEvent(Event::create(EventTypeNames::statechange));
+}
+
 PresentationController* PresentationSession::presentationController()
 {
     if (!frame())