Implement users options handling in login screen.

chrome/browser/chromeos/login/user_manager.cc

 // Copyright (c) 2010 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/chromeos/login/user_manager.h"
 
 #include "app/resource_bundle.h"
 #include "base/compiler_specific.h"
 #include "base/file_path.h"
 #include "base/file_util.h"
@@ skipping 196 matching lines @@
        it < users.end();
        ++it) {
     std::string user_email = it->email();
     // Skip user that we would like to delete.
     if (email != user_email)
       prefs_users->Append(Value::CreateStringValue(user_email));
   }
   prefs->SavePersistentPrefs();
 }
 
+bool UserManager::IsKnownUser(const std::string& email) {
+  std::vector<User> users = GetUsers();
+  for (std::vector<User>::iterator it = users.begin();
+       it < users.end();
+       ++it) {
+    if (it->email() == email)
+      return true;
+  }
+
+  return false;
+}
+
 void UserManager::SetLoggedInUserImage(const SkBitmap& image) {
   if (logged_in_user_.email().empty())
     return;
   logged_in_user_.set_image(image);
   OnImageLoaded(logged_in_user_.email(), image);
 }
 
 void UserManager::SaveUserImage(const std::string& username,
                                 const SkBitmap& image) {
   DCHECK(ChromeThread::CurrentlyOn(ChromeThread::UI));
@@ skipping 57 matching lines @@
 void UserManager::Observe(NotificationType type,
                           const NotificationSource& source,
                           const NotificationDetails& details) {
   if (type == NotificationType::OWNER_KEY_FETCH_ATTEMPT_SUCCEEDED) {
     ChromeThread::PostTask(ChromeThread::FILE, FROM_HERE,
         NewRunnableFunction(&CheckOwnership));
   }
 }
 
 }  // namespace chromeos