Standardize "net" category trace events

net/socket/client_socket_pool_base.cc

Index: net/socket/client_socket_pool_base.cc
diff --git a/net/socket/client_socket_pool_base.cc b/net/socket/client_socket_pool_base.cc
index c4307fb2812adde72a826072e9ed990291c2539f..8c0e236a7253582d17b4f49e72f3372df57c9f46 100644
--- a/net/socket/client_socket_pool_base.cc
+++ b/net/socket/client_socket_pool_base.cc
@@ -19,6 +19,7 @@
 #include "base/trace_event/trace_event.h"
 #include "base/values.h"
 #include "net/base/net_errors.h"
+#include "net/base/trace_constants.h"
 #include "net/log/net_log.h"
 #include "net/log/net_log_event_type.h"
 #include "net/log/net_log_source.h"
@@ -128,7 +129,7 @@ void ConnectJob::SetSocket(std::unique_ptr<StreamSocket> socket) {
 }
 
 void ConnectJob::NotifyDelegateOfCompletion(int rv) {
-  TRACE_EVENT0("net", "ConnectJob::NotifyDelegateOfCompletion");
+  TRACE_EVENT0(kNetTracingCategory, "ConnectJob::NotifyDelegateOfCompletion");
   // The delegate will own |this|.
   Delegate* delegate = delegate_;
   delegate_ = NULL;