Revert of Revert of Remove the last piece of deprecated synchronous IO code.

content/browser/renderer_host/media/audio_renderer_host.cc

Index: content/browser/renderer_host/media/audio_renderer_host.cc
diff --git a/content/browser/renderer_host/media/audio_renderer_host.cc b/content/browser/renderer_host/media/audio_renderer_host.cc
index 7b07fd99c3b57e03ad97d69d5b7bd8c8fcae967a..91cea8365224cc79a0625c6c0793c778f053d59b 100644
--- a/content/browser/renderer_host/media/audio_renderer_host.cc
+++ b/content/browser/renderer_host/media/audio_renderer_host.cc
@@ -357,8 +357,6 @@
     output_device_id = info->device.matched_output_device_id;
 
   // Create the shared memory and share with the renderer process.
-  // For synchronized I/O (if input_channels > 0) then we allocate
-  // extra memory after the output data for the input data.
   uint32 shared_memory_size = AudioBus::CalculateMemorySize(params);
   scoped_ptr<base::SharedMemory> shared_memory(new base::SharedMemory());
   if (!shared_memory->CreateAndMapAnonymous(shared_memory_size)) {