Add more instrumentation for tracking jank in ProxyService creation.

net/proxy/proxy_config_service_win.cc

Index: net/proxy/proxy_config_service_win.cc
diff --git a/net/proxy/proxy_config_service_win.cc b/net/proxy/proxy_config_service_win.cc
index c0c5129fef4acf65133b3442b9699574dd8fb3c0..e75fa39b6005698d6056cc57dba8d2ff57a2a7ee 100644
--- a/net/proxy/proxy_config_service_win.cc
+++ b/net/proxy/proxy_config_service_win.cc
@@ -11,9 +11,10 @@
 #include "base/bind_helpers.h"
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
+#include "base/profiler/scoped_tracker.h"
 #include "base/stl_util.h"
-#include "base/strings/string_util.h"
 #include "base/strings/string_tokenizer.h"
+#include "base/strings/string_util.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/threading/thread_restrictions.h"
 #include "base/win/registry.h"
@@ -62,6 +63,11 @@ void ProxyConfigServiceWin::AddObserver(Observer* observer) {
 }
 
 void ProxyConfigServiceWin::StartWatchingRegistryForChanges() {
+  // TODO(eroman): Remove once crbug.com/454983 is solved.
+  tracked_objects::ScopedTracker tracking_profile(
+      FROM_HERE_WITH_EXPLICIT_FUNCTION(
+          "454983 ProxyConfigServiceWin::StartWatchingRegistryForChanges"));
+
   if (!keys_to_watch_.empty())
     return;  // Already initialized.