Implement setSinkId() for media elements without src.

third_party/WebKit/Source/modules/audio_output_devices/HTMLMediaElementAudioOutputDevice.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 HTMLMediaElementAudioOutputDevice_h
 #define HTMLMediaElementAudioOutputDevice_h
 
 #include "bindings/core/v8/ScriptPromise.h"
 #include "core/dom/ContextLifecycleObserver.h"
 #include "core/dom/ExceptionCode.h"
@@ skipping 11 matching lines @@
     WILL_BE_USING_GARBAGE_COLLECTED_MIXIN(HTMLMediaElementAudioOutputDevice);
     USING_FAST_MALLOC_WILL_BE_REMOVED(HTMLMediaElementAudioOutputDevice);
 public:
     DECLARE_VIRTUAL_TRACE();
     static String sinkId(HTMLMediaElement&);
     static ScriptPromise setSinkId(ScriptState*, HTMLMediaElement&, const String& sinkId);
     static HTMLMediaElementAudioOutputDevice& from(HTMLMediaElement&);
     void setSinkId(const String&);
 
 private:
+    friend class SetSinkIdResolver;

[Peter Beverloo, 2015/11/12 16:45:42]

Why do we need this?

[Guido Urdaneta, 2015/11/12 18:45:44]

We don't. An early version of SetSinkIdResolver required it, and I didn't
realize that the final version does not require it.
Fixed.

     HTMLMediaElementAudioOutputDevice();
     static const char* supplementName();
 
     String m_sinkId;
 };
 
 } // namespace blink
 
 #endif