Standardize "net" category trace events

net/socket/transport_client_socket_pool.cc

Index: net/socket/transport_client_socket_pool.cc
diff --git a/net/socket/transport_client_socket_pool.cc b/net/socket/transport_client_socket_pool.cc
index dbcd7c44c57b89da7e3d82f27c0eda464237850a..56628b8246e1e9fd4745bf9c1d0d1c9c7166ecb0 100644
--- a/net/socket/transport_client_socket_pool.cc
+++ b/net/socket/transport_client_socket_pool.cc
@@ -23,6 +23,7 @@
 #include "net/log/net_log_event_type.h"
 #include "net/log/net_log_source_type.h"
 #include "net/log/net_log_with_source.h"
+#include "net/log/trace_constants.h"
 #include "net/socket/client_socket_factory.h"
 #include "net/socket/client_socket_handle.h"
 #include "net/socket/client_socket_pool_base.h"
@@ -267,7 +268,8 @@ int TransportConnectJob::DoResolveHost() {
 }
 
 int TransportConnectJob::DoResolveHostComplete(int result) {
-  TRACE_EVENT0("net", "TransportConnectJob::DoResolveHostComplete");
+  TRACE_EVENT0(kNetTracingCategory,
+               "TransportConnectJob::DoResolveHostComplete");
   connect_timing_.dns_end = base::TimeTicks::Now();
   // Overwrite connection start time, since for connections that do not go
   // through proxies, |connect_start| should not include dns lookup time.