ListAccounts will return the Gaia ID as well as the email of the account.

chrome/browser/signin/cross_device_promo.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/signin/cross_device_promo.h"
 
 #include "base/metrics/histogram_macros.h"
 #include "base/prefs/pref_service.h"
 #include "base/rand_util.h"
 #include "base/strings/string_number_conversions.h"
@@ skipping 369 matching lines @@
 
 void CrossDevicePromo::UnregisterForCookieChanges() {
   cookie_manager_service_->RemoveObserver(this);
 }
 
 base::Time CrossDevicePromo::GetTimePref(const std::string& pref) {
   return base::Time::FromInternalValue(prefs_->GetInt64(pref));
 }
 
 void CrossDevicePromo::OnGaiaAccountsInCookieUpdated(
-    const std::vector<std::pair<std::string, bool>>& accounts,
+    const std::vector<gaia::ListedAccount>& accounts,
     const GoogleServiceAuthError& error) {
   VLOG(1) << "CrossDevicePromo::OnGaiaAccountsInCookieUpdated. "
           << accounts.size() << " accounts with auth error " << error.state();
   if (error.state() != GoogleServiceAuthError::State::NONE)
     return;
 
   // Multiple accounts seen - clear the pref.
   bool single_account = accounts.size() == 1;
   bool has_pref =
       prefs_->HasPrefPath(prefs::kCrossDevicePromoObservedSingleAccountCookie);
@@ skipping 18 matching lines @@
 }
 
 void CrossDevicePromo::MarkPromoInactive() {
   VLOG(1) << "CrossDevicePromo::MarkPromoInactive.";
   if (prefs_->GetBoolean(prefs::kCrossDevicePromoActive)) {
     prefs_->SetBoolean(prefs::kCrossDevicePromoActive, false);
     FOR_EACH_OBSERVER(CrossDevicePromo::Observer, observer_list_,
                       OnPromoActivationChanged(false));
   }
 }