Add support for midstream audio configuration changes.

media/filters/source_buffer_stream.cc

Index: media/filters/source_buffer_stream.cc
diff --git a/media/filters/source_buffer_stream.cc b/media/filters/source_buffer_stream.cc
index 286300dcdaee4850f78db6a070fa17b1409d3a50..d61fc5ef00c2b6a6378be7d4c988f50bc0587e91 100644
--- a/media/filters/source_buffer_stream.cc
+++ b/media/filters/source_buffer_stream.cc
@@ -1335,7 +1335,7 @@ bool SourceBufferStream::UpdateAudioConfig(const AudioDecoderConfig& config) {
     return false;
   }
 
-  if (audio_configs_[0].samples_per_second() != config.samples_per_second()) {
+  /*if (audio_configs_[0].samples_per_second() != config.samples_per_second()) {
     MEDIA_LOG(log_cb_) << "Audio sample rate changes not allowed.";
     return false;
   }
@@ -1348,7 +1348,7 @@ bool SourceBufferStream::UpdateAudioConfig(const AudioDecoderConfig& config) {
   if (audio_configs_[0].bits_per_channel() != config.bits_per_channel()) {
     MEDIA_LOG(log_cb_) << "Audio bits per channel changes not allowed.";
     return false;
-  }
+  }*/
 
   if (audio_configs_[0].is_encrypted() != config.is_encrypted()) {
     MEDIA_LOG(log_cb_) << "Audio encryption changes not allowed.";