Presentation API: add UMA.

Source/modules/presentation/PresentationAvailability.h

 // Copyright 2015 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.
 
 #ifndef PresentationAvailability_h
 #define PresentationAvailability_h
 
 #include "core/dom/ActiveDOMObject.h"
 #include "core/events/EventTarget.h"
 #include "core/page/PageLifecycleObserver.h"
@@ skipping 19 matching lines @@
 public:
     // For CallbackPromiseAdapter.
     using WebType = bool;
 
     static PresentationAvailability* take(ScriptPromiseResolver*, bool);
     ~PresentationAvailability() override;
 
     // EventTarget implementation.
     const AtomicString& interfaceName() const override;
     ExecutionContext* executionContext() const override;
+    bool addEventListener(const AtomicString& eventType, PassRefPtrWillBeRawPtr<EventListener>, bool capture) override;
 
     // WebPresentationAvailabilityObserver implementation.
     void availabilityChanged(bool) override;
 
     // ActiveDOMObject implementation.
     bool hasPendingActivity() const override;
     void suspend() override;
     void resume() override;
     void stop() override;
 
@@ skipping 22 matching lines @@
     void setState(State);
     void updateListening();
 
     bool m_value;
     State m_state;
 };
 
 } // namespace blink
 
 #endif // PresentationAvailability_h