[Chromecast] Don't DCHECK the result of snd_pcm_status_get_avail

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

 // 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.
 
 #include "chromecast/media/cma/backend/alsa/stream_mixer_alsa.h"
 
 #include <algorithm>
 #include <cmath>
 #include <limits>
 #include <utility>
@@ skipping 746 matching lines @@
         base::Bind(&StreamMixerAlsa::WriteFrames, base::Unretained(this)));
   }
 }
 
 bool StreamMixerAlsa::TryWriteFrames() {
   DCHECK(mixer_task_runner_->BelongsToCurrentThread());
   if (state_ != kStateNormalPlayback) {
     return false;
   }
 
+  const int min_frames_in_buffer =
+      output_samples_per_second_ * kMinBufferedDataMs / 1000;
   int chunk_size = output_samples_per_second_ * kMaxWriteSizeMs / 1000;
   std::vector<InputQueue*> active_inputs;
   for (auto&& input : inputs_) {
     int read_size = input->MaxReadSize();
     if (read_size > 0) {
       active_inputs.push_back(input.get());
       chunk_size = std::min(chunk_size, read_size);
     } else if (input->primary()) {
       if (alsa_->PcmStatus(pcm_, pcm_status_) != 0) {
         LOG(ERROR) << "Failed to get status";
         return false;
       }
 
-      const int min_frames_in_buffer =
-          output_samples_per_second_ * kMinBufferedDataMs / 1000;
       int frames_in_buffer =
           alsa_buffer_size_ - alsa_->PcmStatusGetAvail(pcm_status_);
-      DCHECK_GE(frames_in_buffer, 0);
       if (alsa_->PcmStatusGetState(pcm_status_) == SND_PCM_STATE_XRUN ||
           frames_in_buffer < min_frames_in_buffer) {
         // If there has been (or soon will be) an underrun, continue without the
         // empty primary input stream.
         continue;
       }
 
       // A primary input cannot provide any data, so wait until later.
       retry_write_frames_timer_->Start(
           FROM_HERE, base::TimeDelta::FromMilliseconds(kMinBufferedDataMs / 2),
@@ skipping 148 matching lines @@
   DCHECK(std::find(loopback_observers_.begin(), loopback_observers_.end(),
                    observer) != loopback_observers_.end());
   loopback_observers_.erase(std::remove(loopback_observers_.begin(),
                                         loopback_observers_.end(), observer),
                             loopback_observers_.end());
   observer->OnRemoved();
 }
 
 }  // namespace media
 }  // namespace chromecast