Fix DCHECK when upgrading from an old profile.

chrome/browser/signin/signin_promo.cc

Index: chrome/browser/signin/signin_promo.cc
diff --git a/chrome/browser/signin/signin_promo.cc b/chrome/browser/signin/signin_promo.cc
index a3404a91322bbbaf40d6d4c83b5c345915c9cf65..05fb0b04487b6b655e154a73f74d0cc9967a203a 100644
--- a/chrome/browser/signin/signin_promo.cc
+++ b/chrome/browser/signin/signin_promo.cc
@@ -182,9 +182,18 @@ GURL GetPromoURL(signin_metrics::Source source,
 }
 
 GURL GetReauthURL(Profile* profile, const std::string& account_id) {
+  AccountTrackerService* account_tracker =
+      AccountTrackerServiceFactory::GetForProfile(profile);
   AccountTrackerService::AccountInfo info =
-      AccountTrackerServiceFactory::GetForProfile(profile)->
-          GetAccountInfo(account_id);
+      account_tracker->GetAccountInfo(account_id);
+
+  // Until we switch to gaia id as the account id, we'll assume we can use the
+  // account_id as an email.  This DCHECK makes sure this code is not forgotten
+  // during the migration.
+  DCHECK(!info.email.empty() ||
+      (account_tracker->GetMigrationState() ==
+           AccountTrackerService::MIGRATION_NOT_STARTED));
+  std::string email = info.email.empty() ? account_id : info.email;
 
   signin_metrics::Source source = switches::IsNewAvatarMenu() ?
       signin_metrics::SOURCE_REAUTH : signin_metrics::SOURCE_SETTINGS;
@@ -192,7 +201,7 @@ GURL GetReauthURL(Profile* profile, const std::string& account_id) {
   GURL url = signin::GetPromoURL(
       source, true /* auto_close */,
       switches::IsNewAvatarMenu() /* is_constrained */);
-  url = net::AppendQueryParameter(url, "email", info.email);
+  url = net::AppendQueryParameter(url, "email", email);
   url = net::AppendQueryParameter(url, "validateEmail", "1");
   return net::AppendQueryParameter(url, "readOnlyEmail", "1");
 }