[Chromecast] Remove command-line switch to change the number of mixer output channels

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

Index: chromecast/media/cma/backend/alsa/stream_mixer_alsa_input_impl.cc
diff --git a/chromecast/media/cma/backend/alsa/stream_mixer_alsa_input_impl.cc b/chromecast/media/cma/backend/alsa/stream_mixer_alsa_input_impl.cc
index 2fa15a1005b8c5a581d0c804de76a58ff97a5472..9537a0746137c6cbd286d704aa8cc4caa3d9c797 100644
--- a/chromecast/media/cma/backend/alsa/stream_mixer_alsa_input_impl.cc
+++ b/chromecast/media/cma/backend/alsa/stream_mixer_alsa_input_impl.cc
@@ -45,6 +45,7 @@ namespace media {
 
 namespace {
 
+const int kNumOutputChannels = 2;
 const int64_t kMaxInputQueueUs = 90000;
 const int64_t kFadeMs = 15;
 // Number of samples to report as readable when paused. When paused, the mixer
@@ -111,7 +112,7 @@ void StreamMixerAlsaInputImpl::Initialize(
     double resample_ratio = static_cast<double>(input_samples_per_second_) /
                             mixer_->output_samples_per_second();
     resampler_.reset(new ::media::MultiChannelResampler(
-        mixer_->num_output_channels(), resample_ratio, kDefaultReadSize,
+        kNumOutputChannels, resample_ratio, kDefaultReadSize,
         base::Bind(&StreamMixerAlsaInputImpl::ReadCB, base::Unretained(this))));
     resampler_->PrimeWithSilence();
   }
@@ -192,8 +193,7 @@ MediaPipelineBackendAlsa::RenderingDelay StreamMixerAlsaInputImpl::QueueData(
     const scoped_refptr<DecoderBufferBase>& data) {
   queue_lock_.AssertAcquired();
   if (!data->end_of_stream()) {
-    int frames =
-        data->data_size() / (mixer_->num_output_channels() * sizeof(float));
+    int frames = data->data_size() / (kNumOutputChannels * sizeof(float));
     queue_.push_back(data);
     queued_frames_ += frames;
     queued_frames_including_resampler_ += frames;
@@ -238,7 +238,7 @@ void StreamMixerAlsaInputImpl::AfterWriteFrames(
     queued_frames_ = 0;
     for (const auto& data : queue_)
       queued_frames_ +=
-          data->data_size() / (mixer_->num_output_channels() * sizeof(float));
+          data->data_size() / (kNumOutputChannels * sizeof(float));
     queued_frames_ -= current_buffer_offset_;
     DCHECK_GE(queued_frames_, 0);
     queued_frames_including_resampler_ =
@@ -291,7 +291,7 @@ void StreamMixerAlsaInputImpl::GetResampledData(::media::AudioBus* dest,
                                                 int frames) {
   DCHECK(mixer_task_runner_->BelongsToCurrentThread());
   DCHECK(dest);
-  DCHECK_EQ(mixer_->num_output_channels(), dest->channels());
+  DCHECK_EQ(kNumOutputChannels, dest->channels());
   DCHECK_GE(dest->frames(), frames);
 
   if (state_ == kStatePaused || state_ == kStateDeleted) {
@@ -339,8 +339,8 @@ void StreamMixerAlsaInputImpl::FillFrames(int frame_delay,
       base::AutoLock lock(queue_lock_);
       if (!queue_.empty()) {
         buffer = queue_.front();
-        buffer_frames = buffer->data_size() /
-                        (mixer_->num_output_channels() * sizeof(float));
+        buffer_frames =
+            buffer->data_size() / (kNumOutputChannels * sizeof(float));
         frames_to_copy =
             std::min(frames_left, buffer_frames - current_buffer_offset_);
         // Note that queued_frames_ is not updated until AfterWriteFrames().
@@ -357,7 +357,7 @@ void StreamMixerAlsaInputImpl::FillFrames(int frame_delay,
     if (buffer) {
       const float* buffer_samples =
           reinterpret_cast<const float*>(buffer->data());
-      for (int i = 0; i < mixer_->num_output_channels(); ++i) {
+      for (int i = 0; i < kNumOutputChannels; ++i) {
         const float* buffer_channel = buffer_samples + (buffer_frames * i);
         memcpy(output->channel(i) + frames_filled,
                buffer_channel + buffer_offset, frames_to_copy * sizeof(float));
@@ -397,7 +397,7 @@ void StreamMixerAlsaInputImpl::FadeIn(::media::AudioBus* dest, int frames) {
                          base::Time::kMillisecondsPerSecond;
   for (int f = 0; f < frames && fade_frames_remaining_; ++f) {
     float fade_multiplier = 1.0 - fade_frames_remaining_ / fade_in_frames;
-    for (int c = 0; c < mixer_->num_output_channels(); ++c)
+    for (int c = 0; c < kNumOutputChannels; ++c)
       dest->channel(c)[f] *= fade_multiplier;
     --fade_frames_remaining_;
   }
@@ -410,13 +410,13 @@ void StreamMixerAlsaInputImpl::FadeOut(::media::AudioBus* dest, int frames) {
   for (; f < frames && fade_frames_remaining_; ++f) {
     float fade_multiplier =
         fade_frames_remaining_ / static_cast<float>(fade_out_frames_total_);
-    for (int c = 0; c < mixer_->num_output_channels(); ++c)
+    for (int c = 0; c < kNumOutputChannels; ++c)
       dest->channel(c)[f] *= fade_multiplier;
     --fade_frames_remaining_;
   }
   // Zero remaining frames
   for (; f < frames; ++f) {
-    for (int c = 0; c < mixer_->num_output_channels(); ++c)
+    for (int c = 0; c < kNumOutputChannels; ++c)
       dest->channel(c)[f] = 0.0f;
   }