Lock only permitted where a supervised user is or was.

chrome/browser/profiles/profile_window.cc

 // Copyright 2013 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/profiles/profile_window.h"
 
 #include "base/command_line.h"
 #include "base/files/file_path.h"
 #include "base/prefs/pref_service.h"
 #include "base/strings/string_number_conversions.h"
@@ skipping 296 matching lines @@
         profile, base::Bind(&LockBrowserCloseSuccess));
   }
 }
 
 bool IsLockAvailable(Profile* profile) {
   DCHECK(profile);
   const std::string& hosted_domain = profile->GetPrefs()->
       GetString(prefs::kGoogleServicesHostedDomain);
   return switches::IsNewProfileManagement() &&
          (hosted_domain == Profile::kNoHostedDomainFound ||
-         hosted_domain == "google.com");
+         hosted_domain == "google.com") &&
+         g_browser_process->local_state()->
+             GetBoolean(prefs::kSupervisedUserExistsOrExisted);
 }
 
 void CreateGuestProfileForUserManager(
     const base::FilePath& profile_path_to_focus,
     profiles::UserManagerTutorialMode tutorial_mode,
     profiles::UserManagerProfileSelected profile_open_action,
     const base::Callback<void(Profile*, const std::string&)>& callback) {
   // Create the guest profile, if necessary, and open the User Manager
   // from the guest profile.
   g_browser_process->profile_manager()->CreateProfileAsync(
@@ skipping 92 matching lines @@
     case BrowserWindow::AVATAR_BUBBLE_MODE_SHOW_ERROR:
       *bubble_view_mode = BUBBLE_VIEW_MODE_PROFILE_CHOOSER;
       *tutorial_mode = TUTORIAL_MODE_SHOW_ERROR;
       return;
     default:
       *bubble_view_mode = profiles::BUBBLE_VIEW_MODE_PROFILE_CHOOSER;
   }
 }
 
 }  // namespace profiles