[chromecast] Slew stream volume changes in StreamMixerAlsa.

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

Index: chromecast/media/cma/backend/alsa/stream_mixer_alsa_input_impl.h
diff --git a/chromecast/media/cma/backend/alsa/stream_mixer_alsa_input_impl.h b/chromecast/media/cma/backend/alsa/stream_mixer_alsa_input_impl.h
index fb529e19d586d11b9dec60df885921249ec01ab4..6e4fb3c49797451723a40eed70186fcfb00d2fd4 100644
--- a/chromecast/media/cma/backend/alsa/stream_mixer_alsa_input_impl.h
+++ b/chromecast/media/cma/backend/alsa/stream_mixer_alsa_input_impl.h
@@ -14,6 +14,7 @@
 #include "base/memory/weak_ptr.h"
 #include "base/synchronization/lock.h"
 #include "chromecast/media/cma/backend/alsa/media_pipeline_backend_alsa.h"
+#include "chromecast/media/cma/backend/alsa/slew_volume.h"
 #include "chromecast/media/cma/backend/alsa/stream_mixer_alsa.h"
 #include "chromecast/media/cma/backend/alsa/stream_mixer_alsa_input.h"
 
@@ -120,6 +121,9 @@ class StreamMixerAlsaInputImpl : public StreamMixerAlsa::InputQueue {
                       mixer_rendering_delay) override;
   int MaxReadSize() override;
   void GetResampledData(::media::AudioBus* dest, int frames) override;
+  bool VolumeScaleAccumulate(const float* src,
+                             int frames,
+                             float* dest) override;
   void AfterWriteFrames(const MediaPipelineBackendAlsa::RenderingDelay&
                             mixer_rendering_delay) override;
   void SignalError(StreamMixerAlsaInput::MixerError error) override;
@@ -149,6 +153,7 @@ class StreamMixerAlsaInputImpl : public StreamMixerAlsa::InputQueue {
   double resample_ratio_;
 
   State state_;
+  SlewVolume slew_volume_;
   float volume_multiplier_;
 
   base::Lock queue_lock_;  // Lock for the following queue-related members.