[Chromecast] Resample all audio below 32000 Hz.

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 9c3aa4f6271a3d7e13b277a99b8bf2b4ef0c5a0e..ef2ba7c3e5e112944fc5b967ad3ba23c354c773f 100644
--- a/chromecast/media/cma/backend/alsa/audio_decoder_alsa.cc
+++ b/chromecast/media/cma/backend/alsa/audio_decoder_alsa.cc
@@ -34,7 +34,6 @@ namespace {
 const CastAudioDecoder::OutputFormat kDecoderSampleFormat =
     CastAudioDecoder::kOutputPlanarFloat;
 
-const int kInvalidSampleRate = -1;
 const int64_t kInvalidDelayTimestamp = std::numeric_limits<int64_t>::min();
 
 AudioDecoderAlsa::RenderingDelay kInvalidRenderingDelay() {
@@ -93,7 +92,7 @@ bool AudioDecoderAlsa::Initialize() {
 bool AudioDecoderAlsa::Start(int64_t start_pts) {
   TRACE_FUNCTION_ENTRY0();
   current_pts_ = start_pts;
-  DCHECK_NE(config_.samples_per_second, kInvalidSampleRate);
+  DCHECK(IsValidConfig(config_));
   mixer_input_.reset(new StreamMixerAlsaInput(
       this, config_.samples_per_second, backend_->Primary()));
   mixer_input_->SetVolumeMultiplier(volume_multiplier_);