Redesign the copresence audio handlers.

components/copresence/mediums/audio/audio_recorder.cc

Index: components/copresence/mediums/audio/audio_recorder.cc
diff --git a/components/copresence/mediums/audio/audio_recorder.cc b/components/copresence/mediums/audio/audio_recorder.cc
index 0946ba86bf80cf4caa0526277bd617993523d180..4d36651c4c0cc7c0580163eb9d8e3c55ce371177 100644
--- a/components/copresence/mediums/audio/audio_recorder.cc
+++ b/components/copresence/mediums/audio/audio_recorder.cc
@@ -39,7 +39,7 @@ void AudioBusToString(scoped_ptr<media::AudioBus> source, std::string* buffer) {
 // converts our samples to the required sample rate, interleaves the samples
 // and sends them to the whispernet decoder to process.
 void ProcessSamples(scoped_ptr<media::AudioBus> bus,
-                    const AudioRecorder::DecodeSamplesCallback& callback) {
+                    const AudioRecorder::RecordedSamplesCallback& callback) {
   std::string samples;
   AudioBusToString(bus.Pass(), &samples);
   content::BrowserThread::PostTask(
@@ -50,15 +50,16 @@ void ProcessSamples(scoped_ptr<media::AudioBus> bus,
 
 // Public methods.
 
-AudioRecorder::AudioRecorder(const DecodeSamplesCallback& decode_callback)
+AudioRecorder::AudioRecorder()
     : is_recording_(false),
       stream_(NULL),
-      decode_callback_(decode_callback),
+      temp_conversion_buffer_(NULL),
       total_buffer_frames_(0),
       buffer_frame_index_(0) {
 }
 
-void AudioRecorder::Initialize() {
+void AudioRecorder::Initialize(const RecordedSamplesCallback& decode_callback) {
+  decode_callback_ = decode_callback;
   media::AudioManager::Get()->GetTaskRunner()->PostTask(
       FROM_HERE,
       base::Bind(&AudioRecorder::InitializeOnAudioThread,