Switch OnMoreData() to use AudioBus.

ppapi/native_client/src/shared/ppapi_proxy/plugin_ppb_audio.cc

Index: ppapi/native_client/src/shared/ppapi_proxy/plugin_ppb_audio.cc
diff --git a/ppapi/native_client/src/shared/ppapi_proxy/plugin_ppb_audio.cc b/ppapi/native_client/src/shared/ppapi_proxy/plugin_ppb_audio.cc
index 18558e6370a576a8848024d31cb1264e2047642f..6a4cfd9d7bfbe0de3a887a7f808eea3e29997e4e 100644
--- a/ppapi/native_client/src/shared/ppapi_proxy/plugin_ppb_audio.cc
+++ b/ppapi/native_client/src/shared/ppapi_proxy/plugin_ppb_audio.cc
@@ -30,6 +30,10 @@ size_t ceil64k(size_t n) {
   return (n + 0xFFFF) & (~0xFFFF);
 }
 
+// Hard coded values from PepperPlatformAudioOutputImpl.
+// TODO(???): PPAPI shouldn't hard code these values for all clients.
+enum { kChannels = 2, kBytesPerSample = 2 };
+
 }  // namespace
 
 PluginAudio::PluginAudio() :
@@ -42,7 +46,8 @@ PluginAudio::PluginAudio() :
     thread_id_(),
     thread_active_(false),
     user_callback_(NULL),
-    user_data_(NULL) {
+    user_data_(NULL),
+    audio_buffer_size_(0) {
   DebugPrintf("PluginAudio::PluginAudio\n");
 }
 
@@ -53,10 +58,13 @@ PluginAudio::~PluginAudio() {
     GetInterface()->StopPlayback(resource_);
   // Unmap the shared memory buffer, if present.
   if (shm_buffer_) {
+    audio_bus_.reset();
+    audio_buffer_.reset();
     munmap(shm_buffer_,
            ceil64k(media::TotalSharedMemorySizeInBytes(shm_size_)));
     shm_buffer_ = NULL;
     shm_size_ = 0;
+    audio_buffer_size_ = 0;
   }
   // Close the handles.
   if (shm_ != -1) {
@@ -87,9 +95,15 @@ void PluginAudio::AudioThread(void* self) {
     if ((sizeof(sync_value) != r) || (-1 == sync_value))
       break;
     // Invoke user callback, get next buffer of audio data.
-    audio->user_callback_(audio->shm_buffer_,
-                          audio->shm_size_,
+    audio->user_callback_(audio->audio_buffer_.get(),
+                          audio->audio_buffer_size_,
                           audio->user_data_);
+
+    // Deinterleave the audio data into the shared memory as float.
+    audio->audio_bus_->FromInterleaved(
+        audio->audio_buffer_.get(), audio->audio_bus_->frames(),
+        kBytesPerSample);
+
     // Signal audio backend by writing buffer length at end of buffer.
     // (Note: NaCl applications will always write the entire buffer.)
     media::SetActualDataSizeInBytes(audio->shm_buffer_,
@@ -112,6 +126,14 @@ void PluginAudio::StreamCreated(NaClSrpcImcDescType socket,
                      shm,
                      0);
   if (MAP_FAILED != shm_buffer_) {
+    // Deduce the frame count from the size using hard coded channel count.
+    audio_bus_ = media::AudioBus::WrapMemory(
+        kChannels, shm_size_ / (sizeof(float) * kChannels), shm_buffer_);
+    // Setup integer audio buffer for user audio data.
+    audio_buffer_size_ =
+        audio_bus_->frames() * audio_bus_->channels() * kBytesPerSample;
+    audio_buffer_.reset(new uint8_t[audio_buffer_size_]);
+
     if (state() == AUDIO_PENDING) {
       StartAudioThread();
     } else {
@@ -126,6 +148,7 @@ bool PluginAudio::StartAudioThread() {
   // clear contents of shm buffer before spinning up audio thread
   DebugPrintf("PluginAudio::StartAudioThread\n");
   memset(shm_buffer_, 0, shm_size_);
+  memset(audio_buffer_.get(), 0, audio_buffer_size_);
   const struct PP_ThreadFunctions* thread_funcs = GetThreadCreator();
   if (NULL == thread_funcs->thread_create ||
       NULL == thread_funcs->thread_join) {