Adding instrumentation to locate the source of jankiness.

google_apis/gaia/gaia_auth_fetcher.cc

Index: google_apis/gaia/gaia_auth_fetcher.cc
diff --git a/google_apis/gaia/gaia_auth_fetcher.cc b/google_apis/gaia/gaia_auth_fetcher.cc
index 194f591d5467080b945d1bdf130eb1401ca49061..bd8408cb07615aeb7eb8c7a550e42f1da5ac9262 100644
--- a/google_apis/gaia/gaia_auth_fetcher.cc
+++ b/google_apis/gaia/gaia_auth_fetcher.cc
@@ -10,6 +10,7 @@
 
 #include "base/json/json_reader.h"
 #include "base/json/json_writer.h"
+#include "base/profiler/scoped_profile.h"
 #include "base/strings/string_split.h"
 #include "base/strings/string_util.h"
 #include "base/strings/stringprintf.h"
@@ -929,6 +930,11 @@ void GaiaAuthFetcher::OnGetCheckConnectionInfoFetched(
 }
 
 void GaiaAuthFetcher::OnURLFetchComplete(const net::URLFetcher* source) {
+  // TODO(vadimt): Remove ScopedProfile below once crbug.com/422577 is fixed.
+  tracked_objects::ScopedProfile tracking_profile(
+      FROM_HERE_WITH_EXPLICIT_FUNCTION(
+          "422577 GaiaAuthFetcher::OnURLFetchComplete"));
+
   fetch_pending_ = false;
   // Some of the GAIA requests perform redirects, which results in the final
   // URL of the fetcher not being the original URL requested.  Therefore use