Presentation API: add UMA.

Source/modules/presentation/PresentationAvailability.cpp

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "config.h"
 #include "modules/presentation/PresentationAvailability.h"
 
 #include "bindings/core/v8/ScriptPromiseResolver.h"
 #include "core/dom/Document.h"
 #include "core/events/Event.h"
+#include "core/frame/UseCounter.h"
 #include "modules/EventTargetModulesNames.h"
 #include "modules/presentation/PresentationController.h"
 #include "public/platform/Platform.h"
 #include "public/platform/modules/presentation/WebPresentationClient.h"
 
 namespace blink {
 
 namespace {
 
 WebPresentationClient* presentationClient(ExecutionContext* executionContext)
@@ skipping 34 matching lines @@
 const AtomicString& PresentationAvailability::interfaceName() const
 {
     return EventTargetNames::PresentationAvailability;
 }
 
 ExecutionContext* PresentationAvailability::executionContext() const
 {
     return ActiveDOMObject::executionContext();
 }
 
+bool PresentationAvailability::addEventListener(const AtomicString& eventType, PassRefPtrWillBeRawPtr<EventListener> listener, bool capture)
+{
+    if (eventType == EventTypeNames::change)
+        UseCounter::count(executionContext(), UseCounter::PresentationAvailabilityChangeEventListener);
+
+    return EventTarget::addEventListener(eventType, listener, capture);
+}
+
 void PresentationAvailability::availabilityChanged(bool value)
 {
     if (m_value == value)
         return;
 
     m_value = value;
     dispatchEvent(Event::create(EventTypeNames::change));
 }
 
 bool PresentationAvailability::hasPendingActivity() const
@@ skipping 45 matching lines @@
 }
 
 DEFINE_TRACE(PresentationAvailability)
 {
     RefCountedGarbageCollectedEventTargetWithInlineData<PresentationAvailability>::trace(visitor);
     PageLifecycleObserver::trace(visitor);
     ActiveDOMObject::trace(visitor);
 }
 
 } // namespace