Add username of account that has an auth error.

chrome/browser/extensions/api/identity/account_tracker.cc

Index: chrome/browser/extensions/api/identity/account_tracker.cc
diff --git a/chrome/browser/extensions/api/identity/account_tracker.cc b/chrome/browser/extensions/api/identity/account_tracker.cc
index fd0834ddc5b04d97ab00f3afeddfad7d9c455928..6afc9f97c9aacd384e0ce131226baae4cf58a376 100644
--- a/chrome/browser/extensions/api/identity/account_tracker.cc
+++ b/chrome/browser/extensions/api/identity/account_tracker.cc
@@ -247,6 +247,17 @@ std::string AccountTracker::GetAccountId() const {
     return account_errors_.begin()->first;
 }
 
+std::string AccountTracker::GetUsername() const {
+  std::string id = GetAccountId();
+  if (!id.empty()) {
+    std::map<std::string, AccountState>::const_iterator it =
+        accounts_.find(id);
+    if (it != accounts_.end())
+      return it->second.ids.email;
+  }
+  return std::string();
+}
+
 GoogleServiceAuthError AccountTracker::GetAuthStatus() const {
   if (account_errors_.size() == 0)
     return GoogleServiceAuthError::AuthErrorNone();