[NOT FOR REVIEW] Instrument net/ with trace events.

net/socket/client_socket_handle.cc

Index: net/socket/client_socket_handle.cc
diff --git a/net/socket/client_socket_handle.cc b/net/socket/client_socket_handle.cc
index b177fb6f3b2fa4486e8901f221db8741e70740d4..3d777186bf25002742d549c952630e6e81846a90 100644
--- a/net/socket/client_socket_handle.cc
+++ b/net/socket/client_socket_handle.cc
@@ -13,6 +13,8 @@
 #include "net/base/net_errors.h"
 #include "net/socket/client_socket_pool.h"
 
+#include "base/trace_event/trace_event.h"
+
 namespace net {
 
 ClientSocketHandle::ClientSocketHandle()
@@ -140,6 +142,7 @@ void ClientSocketHandle::SetSocket(scoped_ptr<StreamSocket> s) {
 }
 
 void ClientSocketHandle::OnIOComplete(int result) {
+  TRACE_EVENT0("net", "net::ClientSocketHandle::OnIOComplete");
   CompletionCallback callback = user_callback_;
   user_callback_.Reset();
   HandleInitCompletion(result);