[Sync] Log age of auth tokens on authentication failure

chrome/browser/signin/about_signin_internals_factory.cc

Index: chrome/browser/signin/about_signin_internals_factory.cc
diff --git a/chrome/browser/signin/about_signin_internals_factory.cc b/chrome/browser/signin/about_signin_internals_factory.cc
index 4eb683b1560831290f42f04cfed417e5d0d813ad..98f012836af89d8d999c61d2e362b22acf20ce90 100644
--- a/chrome/browser/signin/about_signin_internals_factory.cc
+++ b/chrome/browser/signin/about_signin_internals_factory.cc
@@ -67,6 +67,7 @@ void AboutSigninInternalsFactory::RegisterUserPrefs(
     const std::string value = pref + ".value";
     const std::string status = pref + ".status";
     const std::string time = pref + ".time";
+    const std::string time_internal = pref + ".time_internal";
     user_prefs->RegisterStringPref(
         value.c_str(),
         std::string(),
@@ -79,6 +80,10 @@ void AboutSigninInternalsFactory::RegisterUserPrefs(
         time.c_str(),
         std::string(),
         user_prefs::PrefRegistrySyncable::UNSYNCABLE_PREF);
+    user_prefs->RegisterInt64Pref(
+        time_internal.c_str(),
+        0,
+        user_prefs::PrefRegistrySyncable::UNSYNCABLE_PREF);
   }
 }