[Blink, RemotePlayback] Dismissing the dialog rejects with NotAllowedError.

third_party/WebKit/Source/modules/remoteplayback/RemotePlayback.h

 // Copyright 2016 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 RemotePlayback_h
 #define RemotePlayback_h
 
 #include "bindings/core/v8/ActiveScriptWrappable.h"
 #include "bindings/core/v8/ScriptPromise.h"
 #include "core/events/EventTarget.h"
+#include "modules/ModulesExport.h"
 #include "platform/heap/Handle.h"
 #include "public/platform/modules/remoteplayback/WebRemotePlaybackClient.h"
 #include "public/platform/modules/remoteplayback/WebRemotePlaybackState.h"
 #include "wtf/text/AtomicString.h"
 #include "wtf/text/WTFString.h"
 
 namespace blink {
 
 class ExecutionContext;
 class HTMLMediaElement;
 class LocalFrame;
 class RemotePlaybackAvailability;
 class ScriptPromiseResolver;
 
-class RemotePlayback final
+class MODULES_EXPORT RemotePlayback final
     : public EventTargetWithInlineData
     , public ActiveScriptWrappable
     , private WebRemotePlaybackClient {
     DEFINE_WRAPPERTYPEINFO();
     USING_GARBAGE_COLLECTED_MIXIN(RemotePlayback);
 public:
     static RemotePlayback* create(HTMLMediaElement&);
 
     // EventTarget implementation.
     const WTF::AtomicString& interfaceName() const override;
     ExecutionContext* getExecutionContext() const override;
 
     ScriptPromise getAvailability(ScriptState*);
     ScriptPromise prompt(ScriptState*);
 
     String state() const;
 
     // ScriptWrappable implementation.
     bool hasPendingActivity() const final;
 
     DEFINE_ATTRIBUTE_EVENT_LISTENER(statechange);
 
     DECLARE_VIRTUAL_TRACE();
 
 private:
+    friend class RemotePlaybackTest;
+
     explicit RemotePlayback(HTMLMediaElement&);
 
     // WebRemotePlaybackClient implementation.
     void stateChanged(WebRemotePlaybackState) override;
     void availabilityChanged(bool available) override;
     void promptCancelled() override;
 
     WebRemotePlaybackState m_state;
     bool m_availability;
     HeapVector<Member<RemotePlaybackAvailability>> m_availabilityObjects;
     Member<HTMLMediaElement> m_mediaElement;
     Member<ScriptPromiseResolver> m_promptPromiseResolver;
 };
 
 } // namespace blink
 
 #endif // RemotePlayback_h