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

chrome/browser/signin/cross_device_promo.cc

Index: chrome/browser/signin/cross_device_promo.cc
diff --git a/chrome/browser/signin/cross_device_promo.cc b/chrome/browser/signin/cross_device_promo.cc
index 095591dfe9e60de8e0a45fab203b4d3a0f449359..eebfbc4971cc284d00e987e5013d315e3a2d85a5 100644
--- a/chrome/browser/signin/cross_device_promo.cc
+++ b/chrome/browser/signin/cross_device_promo.cc
@@ -387,7 +387,7 @@ base::Time CrossDevicePromo::GetTimePref(const std::string& 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();