Use MessageLoopProxy for network message loop.

remoting/protocol/rtcp_writer.h

Index: remoting/protocol/rtcp_writer.h
diff --git a/remoting/protocol/rtcp_writer.h b/remoting/protocol/rtcp_writer.h
index e4a7226a6934925ab65e87772a060b7c7864b262..7ae49dd6319354df12c602116ce66f90fe972011 100644
--- a/remoting/protocol/rtcp_writer.h
+++ b/remoting/protocol/rtcp_writer.h
@@ -7,6 +7,10 @@
 
 #include "net/socket/socket.h"
 
+namespace base {
+class MessageLoopProxy;
+}  // namespace base
+
 namespace remoting {
 
 class CompoundBuffer;
@@ -18,7 +22,7 @@ struct RtcpReceiverReport;
 
 class RtcpWriter {
  public:
-  RtcpWriter();
+  RtcpWriter(base::MessageLoopProxy* message_loop);
   virtual ~RtcpWriter();
 
   // Initializes the writer. Must be called on the thread the socket