[Chromecast] Implement new volume control API

chromecast/media/cma/backend/alsa/audio_decoder_alsa.cc

Index: chromecast/media/cma/backend/alsa/audio_decoder_alsa.cc
diff --git a/chromecast/media/cma/backend/alsa/audio_decoder_alsa.cc b/chromecast/media/cma/backend/alsa/audio_decoder_alsa.cc
index 0221c0a9263c7bd9abbf3c5d5bb15c577bb90f9f..76888353f6dc1d20e90fd878f164a45ee510bd2a 100644
--- a/chromecast/media/cma/backend/alsa/audio_decoder_alsa.cc
+++ b/chromecast/media/cma/backend/alsa/audio_decoder_alsa.cc
@@ -108,9 +108,9 @@ bool AudioDecoderAlsa::Start(int64_t start_pts) {
   TRACE_FUNCTION_ENTRY0();
   current_pts_ = start_pts;
   DCHECK(IsValidConfig(config_));
-  mixer_input_.reset(new StreamMixerAlsaInput(this, config_.samples_per_second,
-                                              backend_->Primary(),
-                                              backend_->DeviceId()));
+  mixer_input_.reset(new StreamMixerAlsaInput(
+      this, config_.samples_per_second, backend_->Primary(),
+      backend_->DeviceId(), backend_->ContentType()));
   mixer_input_->SetVolumeMultiplier(volume_multiplier_);
   // Create decoder_ if necessary. This can happen if Stop() was called, and
   // SetConfig() was not called since then.
@@ -238,9 +238,9 @@ bool AudioDecoderAlsa::SetConfig(const AudioConfig& config) {
     // Destroy the old input first to ensure that the mixer output sample rate
     // is updated.
     mixer_input_.reset();
-    mixer_input_.reset(new StreamMixerAlsaInput(this, config.samples_per_second,
-                                                backend_->Primary(),
-                                                backend_->DeviceId()));
+    mixer_input_.reset(new StreamMixerAlsaInput(
+        this, config.samples_per_second, backend_->Primary(),
+        backend_->DeviceId(), backend_->ContentType()));
     mixer_input_->SetVolumeMultiplier(volume_multiplier_);
     pending_output_frames_ = kNoPendingOutput;
   }