ScopedTrackers to help pin down where IOThread::InitSystemRequestContextOnIOThread is janky

chrome/browser/net/proxy_service_factory.cc

Index: chrome/browser/net/proxy_service_factory.cc
diff --git a/chrome/browser/net/proxy_service_factory.cc b/chrome/browser/net/proxy_service_factory.cc
index c73f3c725ce6539ef5bff22f1230df35fec09189..6bb3f38e5f25d3746c17c1392a979869715eefe1 100644
--- a/chrome/browser/net/proxy_service_factory.cc
+++ b/chrome/browser/net/proxy_service_factory.cc
@@ -5,6 +5,7 @@
 #include "chrome/browser/net/proxy_service_factory.h"
 
 #include "base/command_line.h"
+#include "base/profiler/scoped_tracker.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/threading/thread.h"
 #include "chrome/browser/browser_process.h"
@@ -94,6 +95,11 @@ net::ProxyService* ProxyServiceFactory::CreateProxyService(
     bool quick_check_enabled) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
 
+  // TODO(michaeln): Remove ScopedTracker below once crbug.com/454983 is fixed.
+  tracked_objects::ScopedTracker tracking_profile(
+      FROM_HERE_WITH_EXPLICIT_FUNCTION(
+          "454983 ProxyServiceFactory::CreateProxyService"));
+
 #if defined(OS_IOS)
   bool use_v8 = false;
 #else