chromecast: Cleanup class/struct fwd declarations

chromecast/media/cma/backend/alsa/stream_mixer_alsa.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 CHROMECAST_MEDIA_CMA_BACKEND_ALSA_STREAM_MIXER_ALSA_H_
 #define CHROMECAST_MEDIA_CMA_BACKEND_ALSA_STREAM_MIXER_ALSA_H_
 
 #include <alsa/asoundlib.h>
 #include <stdint.h>
 
@@ skipping 10 matching lines @@
 #include "chromecast/media/cma/backend/alsa/stream_mixer_alsa_input.h"
 #include "chromecast/public/cast_media_shlib.h"
 
 namespace media {
 class AudioBus;
 }  // namespace media
 
 namespace chromecast {
 namespace media {
 class AlsaWrapper;
-class StreamMixerAlsaInputImpl;
 
 // Mixer implementation. The mixer has one or more input queues; these can be
 // added/removed at any time. When an input source pushes frames to an input
 // queue, the queue should call StreamMixerAlsa::WriteFrames(); this causes
 // the mixer to attempt to mix and write out as many frames as possible. To do
 // this, the mixer determines how many frames can be read from all inputs (ie,
 // it gets the maximum number of frames that can be read from each input, and
 // uses the minimum value). Assuming that all primary inputs have some data
 // available, the calculated number of frames are pulled from each input (maybe
 // resampled, if the input's incoming sample rate is not equal to the mixer's
@@ skipping 208 matching lines @@
   std::unique_ptr<AudioFilterInterface> post_loopback_filter_;
   int silence_frames_filtered_ = 0;
 
   DISALLOW_COPY_AND_ASSIGN(StreamMixerAlsa);
 };
 
 }  // namespace media
 }  // namespace chromecast
 
 #endif  // CHROMECAST_MEDIA_CMA_BACKEND_ALSA_STREAM_MIXER_ALSA_H_