[Athena] Extract Chrome OS authentication stack

chrome/browser/chromeos/login/helper.cc

Index: chrome/browser/chromeos/login/helper.cc
diff --git a/chrome/browser/chromeos/login/helper.cc b/chrome/browser/chromeos/login/helper.cc
index 38809d6d2d5db440a2e357d86c9515d7998925ac..cdea1e2f1f43fa4c2bfd67b926d719c8b79f4496 100644
--- a/chrome/browser/chromeos/login/helper.cc
+++ b/chrome/browser/chromeos/login/helper.cc
@@ -12,7 +12,6 @@
 #include "chromeos/network/network_handler.h"
 #include "chromeos/network/network_state.h"
 #include "chromeos/network/network_state_handler.h"
-#include "google_apis/gaia/gaia_auth_util.h"
 #include "grit/generated_resources.h"
 #include "grit/theme_resources.h"
 #include "third_party/cros_system_api/dbus/service_constants.h"
@@ -45,12 +44,6 @@ int GetCurrentUserImageSize() {
 
 namespace login {
 
-std::string CanonicalizeUserID(const std::string& user_id) {
-  if (user_id == UserManager::kGuestUserName)
-    return user_id;
-  return gaia::CanonicalizeEmail(user_id);
-}
-
 bool LoginScrollIntoViewEnabled() {
   return !CommandLine::ForCurrentProcess()->HasSwitch(
       chromeos::switches::kDisableLoginScrollIntoView);