Revert of Made MixerAudioSource a pure interface.

webrtc/modules/audio_mixer/audio_source_with_mix_status.h

Index: webrtc/modules/audio_mixer/audio_source_with_mix_status.h
diff --git a/webrtc/modules/audio_mixer/audio_source_with_mix_status.h b/webrtc/modules/audio_mixer/audio_source_with_mix_status.h
deleted file mode 100644
index 3489ec46ec722e7ab32fb33c38206c17f0b0a73d..0000000000000000000000000000000000000000
--- a/webrtc/modules/audio_mixer/audio_source_with_mix_status.h
+++ /dev/null
@@ -1,45 +0,0 @@
-/*
- *  Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
- *
- *  Use of this source code is governed by a BSD-style license
- *  that can be found in the LICENSE file in the root of the source
- *  tree. An additional intellectual property rights grant can be found
- *  in the file PATENTS.  All contributing project authors may
- *  be found in the AUTHORS file in the root of the source tree.
- */
-
-#ifndef WEBRTC_MODULES_AUDIO_MIXER_AUDIO_SOURCE_WITH_MIX_STATUS_H_
-#define WEBRTC_MODULES_AUDIO_MIXER_AUDIO_SOURCE_WITH_MIX_STATUS_H_
-
-#include "webrtc/modules/audio_mixer/audio_mixer_defines.h"
-
-namespace webrtc {
-
-// A class that holds a mixer participant and its mixing status.
-class AudioSourceWithMixStatus {
- public:
-  explicit AudioSourceWithMixStatus(MixerAudioSource* audio_source);
-  ~AudioSourceWithMixStatus();
-
-  AudioSourceWithMixStatus(const AudioSourceWithMixStatus&) = default;
-
-  // Returns true if the audio source was mixed this mix iteration.
-  bool IsMixed() const;
-
-  // Returns true if the audio source was mixed previous mix
-  // iteration.
-  bool WasMixed() const;
-
-  // Updates the mixed status.
-  void SetIsMixed(const bool mixed);
-  void ResetMixedStatus();
-  MixerAudioSource* audio_source() const;
-
- private:
-  MixerAudioSource* audio_source_ = nullptr;
-  bool is_mixed_ = false;
-};
-
-}  // namespace webrtc
-
-#endif  // WEBRTC_MODULES_AUDIO_MIXER_AUDIO_SOURCE_WITH_MIX_STATUS_H_