Add more instrumentation for tracking jank in ProxyService creation.

net/proxy/proxy_service.cc

Index: net/proxy/proxy_service.cc
diff --git a/net/proxy/proxy_service.cc b/net/proxy/proxy_service.cc
index cd6e376be5299c05af52adcad7631eb14a38a358..9e20db6e4fa974a380b3071e15a30ead0688da32 100644
--- a/net/proxy/proxy_service.cc
+++ b/net/proxy/proxy_service.cc
@@ -904,6 +904,9 @@ ProxyService::ProxyService(ProxyConfigService* config_service,
       stall_proxy_auto_config_delay_(TimeDelta::FromMilliseconds(
           kDelayAfterNetworkChangesMs)),
       quick_check_enabled_(true) {
+  // TODO(eroman): Remove once crbug.com/454983 is solved.
+  tracked_objects::ScopedTracker tracking_profile(
+      FROM_HERE_WITH_EXPLICIT_FUNCTION("454983 ProxyService::ProxyService"));
   NetworkChangeNotifier::AddIPAddressObserver(this);
   NetworkChangeNotifier::AddDNSObserver(this);
   ResetConfigService(config_service);
@@ -1421,6 +1424,11 @@ ProxyService::State ProxyService::ResetProxyConfig(bool reset_fetched_config) {
 
 void ProxyService::ResetConfigService(
     ProxyConfigService* new_proxy_config_service) {
+  // TODO(eroman): Remove once crbug.com/454983 is solved.
+  tracked_objects::ScopedTracker tracking_profile(
+      FROM_HERE_WITH_EXPLICIT_FUNCTION(
+          "454983 ProxyService::ResetConfigService"));
+
   DCHECK(CalledOnValidThread());
   State previous_state = ResetProxyConfig(true);