Add TRACE_EVENT macros to net.

net/proxy/proxy_resolver_v8_tracing.cc

Index: net/proxy/proxy_resolver_v8_tracing.cc
diff --git a/net/proxy/proxy_resolver_v8_tracing.cc b/net/proxy/proxy_resolver_v8_tracing.cc
index a9fdeeb771db19ae5e9ea4dbbcb83c0bdbac3b95..230c4f9c11f5655095162fc28795675627542e36 100644
--- a/net/proxy/proxy_resolver_v8_tracing.cc
+++ b/net/proxy/proxy_resolver_v8_tracing.cc
@@ -20,6 +20,7 @@
 #include "base/thread_task_runner_handle.h"
 #include "base/threading/thread.h"
 #include "base/threading/thread_restrictions.h"
+#include "base/trace_event/trace_event.h"
 #include "net/base/address_list.h"
 #include "net/base/net_errors.h"
 #include "net/base/network_interfaces.h"
@@ -578,6 +579,7 @@ void Job::ExecuteNonBlocking() {
 }
 
 int Job::ExecuteProxyResolver() {
+  TRACE_EVENT0("net", "Job::ExecuteProxyResolver");
   int result = ERR_UNEXPECTED;  // Initialized to silence warnings.
 
   switch (operation_) {