Create new class "CastTransport", which encapsulates the message read and write event loops.

extensions/browser/api/cast_channel/logger.cc

Index: extensions/browser/api/cast_channel/logger.cc
diff --git a/extensions/browser/api/cast_channel/logger.cc b/extensions/browser/api/cast_channel/logger.cc
index 823b4c320877e84c3141879d8ce81d92e9bb8dd9..209b6f67615c8af84707df9735d5f876834220e2 100644
--- a/extensions/browser/api/cast_channel/logger.cc
+++ b/extensions/browser/api/cast_channel/logger.cc
@@ -119,7 +119,7 @@ Logger::Logger(scoped_ptr<base::TickClock> clock,
 Logger::~Logger() {
 }
 
-void Logger::LogNewSocketEvent(const CastSocket& cast_socket) {
+void Logger::LogNewSocketEvent(const CastSocketImpl& cast_socket) {
   DCHECK(thread_checker_.CalledOnValidThread());
 
   int channel_id = cast_socket.id();