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

net/socket/socket_posix.cc

Index: net/socket/socket_posix.cc
diff --git a/net/socket/socket_posix.cc b/net/socket/socket_posix.cc
index 96892891d097eda59ee1c4ac5b65266532ebf636..61266484e30fb1bcb0d4fd42bcd2200c979ae586 100644
--- a/net/socket/socket_posix.cc
+++ b/net/socket/socket_posix.cc
@@ -18,6 +18,8 @@
 #include "net/base/net_errors.h"
 #include "net/base/sockaddr_storage.h"
 
+#include "base/trace_event/trace_event.h"
+
 namespace net {
 
 namespace {
@@ -348,6 +350,7 @@ void SocketPosix::DetachFromThread() {
 }
 
 void SocketPosix::OnFileCanReadWithoutBlocking(int fd) {
+  TRACE_EVENT0("net", "net::SocketPosix::OnFileCanReadWithoutBlocking");
   DCHECK(!accept_callback_.is_null() || !read_callback_.is_null());
   if (!accept_callback_.is_null()) {
     AcceptCompleted();