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

net/base/address_tracker_linux.cc

Index: net/base/address_tracker_linux.cc
diff --git a/net/base/address_tracker_linux.cc b/net/base/address_tracker_linux.cc
index 59d732c90d79f60a4690cb6278ae1a974b36e6dc..adb097d4dbae92eb62f21effdbd05681b8cf4f22 100644
--- a/net/base/address_tracker_linux.cc
+++ b/net/base/address_tracker_linux.cc
@@ -15,6 +15,8 @@
 #include "base/threading/thread_restrictions.h"
 #include "net/base/network_interfaces_linux.h"
 
+#include "base/trace_event/trace_event.h"
+
 namespace net {
 namespace internal {
 
@@ -413,6 +415,7 @@ void AddressTrackerLinux::HandleMessage(char* buffer,
 }
 
 void AddressTrackerLinux::OnFileCanReadWithoutBlocking(int fd) {
+  TRACE_EVENT0("net", "net::AddressTrackerLinux::OnFileCanReadWithoutBlocking");
   DCHECK_EQ(netlink_fd_, fd);
   bool address_changed;
   bool link_changed;