Revert of [Chromecast] Process streams with different post-processing.

chromecast/media/cma/backend/alsa/stream_mixer_alsa.h

Index: chromecast/media/cma/backend/alsa/stream_mixer_alsa.h
diff --git a/chromecast/media/cma/backend/alsa/stream_mixer_alsa.h b/chromecast/media/cma/backend/alsa/stream_mixer_alsa.h
index b522f09024cb274daf1aea6adfe5a1775ded5788..53a48911f72ae92fe6fed42b1db7703d52aab2fd 100644
--- a/chromecast/media/cma/backend/alsa/stream_mixer_alsa.h
+++ b/chromecast/media/cma/backend/alsa/stream_mixer_alsa.h
@@ -28,7 +28,6 @@
 namespace chromecast {
 namespace media {
 class AlsaWrapper;
-class FilterGroup;
 
 // 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
@@ -68,11 +67,6 @@
     // precedence for sample rates and will dictate when data is polled.
     virtual bool primary() const = 0;
 
-    // Returns a string describing the content type class.
-    // Should be from chromecast/media/base/audio_device_ids.h
-    // or media/audio/audio_device_description.h
-    virtual std::string device_id() const = 0;
-
     // Returns true if PrepareToDelete() has been called.
     virtual bool IsDeleting() const = 0;
 
@@ -80,12 +74,6 @@
     // input can correctly determine the mixer's output sample rate.
     virtual void Initialize(const MediaPipelineBackendAlsa::RenderingDelay&
                                 mixer_rendering_delay) = 0;
-
-    // Sets and gets the FilterGroup the InputQueue matches.
-    // This is determined at creation to save time matching the InputQueue
-    // to a FilterGroup every time it needs to be mixed.
-    virtual void set_filter_group(FilterGroup* filter_group) = 0;
-    virtual FilterGroup* filter_group() = 0;
 
     // Returns the maximum number of frames that can be read from this input
     // stream without filling with zeros. This should return 0 if the queue is
@@ -207,11 +195,10 @@
 
   void WriteFrames();
   bool TryWriteFrames();
-  void WriteMixedPcm(std::vector<uint8_t>* interleaved, int frames);
+  void WriteMixedPcm(const ::media::AudioBus& mixed, int frames,
+      bool is_silence);
   void UpdateRenderingDelay(int newly_pushed_frames);
-  size_t InterleavedSize(int frames);
   ssize_t BytesPerOutputFormatSample();
-  void ResizeBuffersIfNecessary(int chunk_size);
 
   static bool single_threaded_for_test_;
 
@@ -242,14 +229,25 @@
   std::vector<std::unique_ptr<InputQueue>> inputs_;
   std::vector<std::unique_ptr<InputQueue>> ignored_inputs_;
   MediaPipelineBackendAlsa::RenderingDelay rendering_delay_;
+  // Buffer to write final interleaved data before sending to snd_pcm_writei().
+  std::vector<uint8_t> interleaved_;
+
+  // Buffers that hold audio data while it is mixed, before it is passed to the
+  // ALSA layer. These are kept as members of this class to minimize copies and
+  // allocations.
+  std::unique_ptr<::media::AudioBus> temp_;
+  std::unique_ptr<::media::AudioBus> mixed_;
 
   std::unique_ptr<base::Timer> retry_write_frames_timer_;
 
   int check_close_timeout_;
   std::unique_ptr<base::Timer> check_close_timer_;
 
-  std::vector<std::unique_ptr<FilterGroup>> filter_groups_;
   std::vector<CastMediaShlib::LoopbackAudioObserver*> loopback_observers_;
+
+  std::unique_ptr<AudioFilterInterface> pre_loopback_filter_;
+  std::unique_ptr<AudioFilterInterface> post_loopback_filter_;
+  int silence_frames_filtered_ = 0;
 
   DISALLOW_COPY_AND_ASSIGN(StreamMixerAlsa);
 };