We should use UserID object to identify users instead of username.

components/policy/core/browser/browser_policy_connector.cc

Index: components/policy/core/browser/browser_policy_connector.cc
diff --git a/components/policy/core/browser/browser_policy_connector.cc b/components/policy/core/browser/browser_policy_connector.cc
index c4768783fc381282b55d9973f13c28b7813e283e..ac6ba892ff68d653984cd1eae092cac563c62ad4 100644
--- a/components/policy/core/browser/browser_policy_connector.cc
+++ b/components/policy/core/browser/browser_policy_connector.cc
@@ -24,6 +24,7 @@
 #include "components/policy/core/common/policy_service_impl.h"
 #include "components/policy/core/common/policy_statistics_collector.h"
 #include "components/policy/core/common/policy_switches.h"
+#include "components/user_manager/user_id.h"
 #include "google_apis/gaia/gaia_auth_util.h"
 #include "net/url_request/url_request_context_getter.h"
 #include "policy/policy_constants.h"
@@ -214,16 +215,17 @@ void BrowserPolicyConnector::SetPolicyProviderForTesting(
 }
 
 // static
-bool BrowserPolicyConnector::IsNonEnterpriseUser(const std::string& username) {
-  if (username.empty() || username.find('@') == std::string::npos) {
-    // An empty username means incognito user in case of ChromiumOS and
+bool BrowserPolicyConnector::IsNonEnterpriseUser(const user_manager::UserID& user_id) {
+  const std::string& email = user_id.GetUserEmail();
+  if (email.empty() || email.find('@') == std::string::npos) {
+    // An empty email means incognito user in case of ChromiumOS and
     // no logged-in user in case of Chromium (SigninService). Many tests use
     // nonsense email addresses (e.g. 'test') so treat those as non-enterprise
     // users.
     return true;
   }
   const base::string16 domain = base::UTF8ToUTF16(
-      gaia::ExtractDomainName(gaia::CanonicalizeEmail(username)));
+      gaia::ExtractDomainName(gaia::CanonicalizeEmail(email)));
   for (size_t i = 0; i < arraysize(kNonManagedDomainPatterns); i++) {
     base::string16 pattern = base::WideToUTF16(kNonManagedDomainPatterns[i]);
     if (MatchDomain(domain, pattern, i))