Work on improving PpbAudioConfig:RecommendSampleFrameCount

content/renderer/pepper_plugin_delegate_impl.cc

Index: content/renderer/pepper_plugin_delegate_impl.cc
===================================================================
--- content/renderer/pepper_plugin_delegate_impl.cc	(revision 118765)
+++ content/renderer/pepper_plugin_delegate_impl.cc	(working copy)
@@ -36,6 +36,7 @@
 #include "content/renderer/gpu/gpu_channel_host.h"
 #include "content/renderer/gpu/renderer_gl_context.h"
 #include "content/renderer/gpu/webgraphicscontext3d_command_buffer_impl.h"
+#include "content/renderer/media/audio_hardware.h"
 #include "content/renderer/media/audio_input_message_filter.h"
 #include "content/renderer/media/audio_message_filter.h"
 #include "content/renderer/media/video_capture_impl_manager.h"
@@ -241,7 +242,12 @@
   client_ = client;
 
   AudioParameters params;
-  params.format = AudioParameters::AUDIO_PCM_LINEAR;
+  // Use the low latency back end if the client request is compatible.
+  if (sample_rate == audio_hardware::GetOutputSampleRate() &&
+      sample_count % audio_hardware::GetOutputBufferSize() == 0)
+    params.format = AudioParameters::AUDIO_PCM_LOW_LATENCY;
+  else
+    params.format = AudioParameters::AUDIO_PCM_LINEAR;
   params.channels = 2;
   params.sample_rate = sample_rate;
   params.bits_per_sample = 16;