Use correct thread for audio capturing and encoding.

remoting/host/chromoting_host.cc

Index: remoting/host/chromoting_host.cc
diff --git a/remoting/host/chromoting_host.cc b/remoting/host/chromoting_host.cc
index 6fe3d11a7d756bf17e501dd7c21a935850538791..8abeda203ae99176b1d9ca9b5e42913841d12c17 100644
--- a/remoting/host/chromoting_host.cc
+++ b/remoting/host/chromoting_host.cc
@@ -59,11 +59,13 @@ ChromotingHost::ChromotingHost(
     SignalStrategy* signal_strategy,
     DesktopEnvironmentFactory* desktop_environment_factory,
     scoped_ptr<protocol::SessionManager> session_manager,
+    scoped_refptr<base::SingleThreadTaskRunner> audio_task_runner,
     scoped_refptr<base::SingleThreadTaskRunner> capture_task_runner,
     scoped_refptr<base::SingleThreadTaskRunner> encode_task_runner,
     scoped_refptr<base::SingleThreadTaskRunner> network_task_runner)
     : desktop_environment_factory_(desktop_environment_factory),
       session_manager_(session_manager.Pass()),
+      audio_task_runner_(audio_task_runner),
       capture_task_runner_(capture_task_runner),
       encode_task_runner_(encode_task_runner),
       network_task_runner_(network_task_runner),
@@ -311,6 +313,7 @@ void ChromotingHost::OnIncomingSession(
       new protocol::ConnectionToClient(session));
   scoped_refptr<ClientSession> client = new ClientSession(
       this,
+      audio_task_runner_,
       capture_task_runner_,
       encode_task_runner_,
       network_task_runner_,