Add support for midstream audio configuration changes.

media/base/audio_converter.cc

Index: media/base/audio_converter.cc
diff --git a/media/base/audio_converter.cc b/media/base/audio_converter.cc
index cdc6642b5f18f28a205f43def5321365f669b77b..81f9dc6396131ed747cfabc2f1020a5a63eda892 100644
--- a/media/base/audio_converter.cc
+++ b/media/base/audio_converter.cc
@@ -28,7 +28,9 @@ AudioConverter::AudioConverter(const AudioParameters& input_params,
     : chunk_size_(output_params.frames_per_buffer()),
       downmix_early_(false),
       resampler_frame_delay_(0),
-      input_channel_count_(input_params.channels()) {
+      input_channel_count_(input_params.channels()),
+      io_sample_rate_ratio_(input_params.sample_rate() /
+                           static_cast<double>(output_params.sample_rate())) {
   CHECK(input_params.IsValid());
   CHECK(output_params.IsValid());
 
@@ -48,14 +50,12 @@ AudioConverter::AudioConverter(const AudioParameters& input_params,
   if (input_params.sample_rate() != output_params.sample_rate()) {
     DVLOG(1) << "Resampling from " << input_params.sample_rate() << " to "
              << output_params.sample_rate();
-    const double io_sample_rate_ratio = input_params.sample_rate() /
-        static_cast<double>(output_params.sample_rate());
     const int request_size = disable_fifo ? SincResampler::kDefaultRequestSize :
         input_params.frames_per_buffer();
     resampler_.reset(new MultiChannelResampler(
         downmix_early_ ? output_params.channels() :
             input_params.channels(),
-        io_sample_rate_ratio, request_size, base::Bind(
+        io_sample_rate_ratio_, request_size, base::Bind(
             &AudioConverter::ProvideInput, base::Unretained(this))));
   }
 
@@ -115,6 +115,13 @@ int AudioConverter::ChunkSize() const {
   return resampler_->ChunkSize();
 }
 
+int AudioConverter::RequestSize() const {
+  if (resampler_)
+    return audio_fifo_ ? chunk_size_
+                       : SincResampler::kDefaultRequestSize;
+  return chunk_size_;
+}
+
 void AudioConverter::ConvertWithDelay(const base::TimeDelta& initial_delay,
                                       AudioBus* dest) {
   initial_delay_ = initial_delay;