Disable token handle fetching on some devices

BUG=484690
R=nkostylev@chromium.org

Review URL: https://codereview.chromium.org/1138883003

Cr-Commit-Position: refs/heads/master@{#329828}

chrome/browser/chromeos/login/existing_user_controller.cc

@@ -1236,7 +1236,7 @@ void ExistingUserController::OnOAuth2TokensFetched(
     OnAuthFailure(AuthFailure(AuthFailure::FAILED_TO_INITIALIZE_TOKEN));
     return;
   }
-  if (StartupUtils::IsWebviewSigninEnabled()) {
+  if (StartupUtils::IsWebviewSigninEnabled() && TokenHandlesEnabled()) {
     if (!token_handle_util_.get()) {
       token_handle_util_.reset(
           new TokenHandleUtil(user_manager::UserManager::Get()));
@@ -1260,4 +1260,14 @@ void ExistingUserController::OnTokenHandleObtained(
   }
 }
 
+bool ExistingUserController::TokenHandlesEnabled() {
+  bool ephemeral_users_enabled = false;
+  bool show_names_on_signin = true;
+  cros_settings_->GetBoolean(kAccountsPrefEphemeralUsersEnabled,
+                             &ephemeral_users_enabled);
+  cros_settings_->GetBoolean(kAccountsPrefShowUserNamesOnSignIn,
+                             &show_names_on_signin);
+  return show_names_on_signin && !ephemeral_users_enabled;
+}
+
 }  // namespace chromeos

chrome/browser/chromeos/login/existing_user_controller.h

@@ -247,6 +247,9 @@ class ExistingUserController : public LoginDisplay::Delegate,
   void OnTokenHandleObtained(const user_manager::UserID& id,
                              TokenHandleUtil::TokenHandleStatus status);
 
+  // Returns |true| if token handles should be used on this device.
+  bool TokenHandlesEnabled();
+
   // Public session auto-login timer.
   scoped_ptr<base::OneShotTimer<ExistingUserController> > auto_login_timer_;