Use a separate thread for audio capturing and encoding.

remoting/host/chromoting_host_context.cc

Index: remoting/host/chromoting_host_context.cc
diff --git a/remoting/host/chromoting_host_context.cc b/remoting/host/chromoting_host_context.cc
index 480de732922a9282de5dac6a984b884150f6f2ec..5518febcc6d19a83d48e085108075d63da1b7578 100644
--- a/remoting/host/chromoting_host_context.cc
+++ b/remoting/host/chromoting_host_context.cc
@@ -17,6 +17,7 @@ ChromotingHostContext::ChromotingHostContext(
     : network_thread_("ChromotingNetworkThread"),
       capture_thread_("ChromotingCaptureThread"),
       encode_thread_("ChromotingEncodeThread"),
+      audio_thread_("ChromotingAudioThread"),
       desktop_thread_("ChromotingDesktopThread"),
       file_thread_("ChromotingFileIOThread"),
       ui_task_runner_(ui_task_runner) {
@@ -50,6 +51,10 @@ base::SingleThreadTaskRunner* ChromotingHostContext::encode_task_runner() {
   return encode_thread_.message_loop_proxy();
 }
 
+base::SingleThreadTaskRunner* ChromotingHostContext::audio_task_runner() {
+  return audio_thread_.message_loop_proxy();
+}
+
 base::SingleThreadTaskRunner* ChromotingHostContext::network_task_runner() {
   return network_thread_.message_loop_proxy();
 }