Presentation API: add UMA.

Source/modules/presentation/PresentationRequest.cpp

Index: Source/modules/presentation/PresentationRequest.cpp
diff --git a/Source/modules/presentation/PresentationRequest.cpp b/Source/modules/presentation/PresentationRequest.cpp
index f18ccffbce35dc8f60adf2f4ed314a7416f34497..a5f809ce614b09e47b924cbf4101a7cb818058ee 100644
--- a/Source/modules/presentation/PresentationRequest.cpp
+++ b/Source/modules/presentation/PresentationRequest.cpp
@@ -11,6 +11,7 @@
 #include "bindings/core/v8/ScriptPromiseResolver.h"
 #include "core/dom/Document.h"
 #include "core/dom/ExecutionContext.h"
+#include "core/frame/UseCounter.h"
 #include "modules/EventTargetModules.h"
 #include "modules/presentation/PresentationAvailability.h"
 #include "modules/presentation/PresentationController.h"
@@ -60,6 +61,14 @@ ExecutionContext* PresentationRequest::executionContext() const
     return ActiveDOMObject::executionContext();
 }
 
+bool PresentationRequest::addEventListener(const AtomicString& eventType, PassRefPtrWillBeRawPtr<EventListener> listener, bool capture)
+{
+    if (eventType == EventTypeNames::sessionconnect)
+        UseCounter::count(executionContext(), UseCounter::PresentationRequestSessionConnectEventListener);
+
+    return EventTarget::addEventListener(eventType, listener, capture);
+}
+
 bool PresentationRequest::hasPendingActivity() const
 {
     // Prevents garbage collecting of this object when not hold by another