Implement setSinkId() for media elements without src.

third_party/WebKit/Source/web/AudioOutputDeviceClientImpl.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 AudioOutputDeviceClientImpl_h
+#define AudioOutputDeviceClientImpl_h
+
+#include "modules/audio_output_devices/AudioOutputDeviceClient.h"
+#include "platform/heap/Handle.h"
+
+namespace blink {
+
+class AudioOutputDeviceClientImpl : public NoBaseWillBeGarbageCollectedFinalized<AudioOutputDeviceClientImpl>, public AudioOutputDeviceClient {
+    WILL_BE_USING_GARBAGE_COLLECTED_MIXIN(AudioOutputDeviceClientImpl);
+    WTF_MAKE_NONCOPYABLE(AudioOutputDeviceClientImpl);
+public:
+    static PassOwnPtrWillBeRawPtr<AudioOutputDeviceClientImpl> create();
+
+    ~AudioOutputDeviceClientImpl() override;
+
+    // AudioOutputDeviceClient implementation.
+    void checkIfAudioSinkExistsAndIsAuthorized(ExecutionContext*, const WebString& sinkId, PassOwnPtr<WebSetSinkIdCallbacks>) override;
+
+    // NoBaseWillBeGarbageCollectedFinalized implementation.
+    DEFINE_INLINE_VIRTUAL_TRACE() { AudioOutputDeviceClient::trace(visitor); }
+
+private:
+    AudioOutputDeviceClientImpl();
+};
+
+} // namespace blink
+
+#endif // AudioOutputDeviceClientImpl_h