[Smart Lock] Add a setting to require close proximity in order for unlocking to work.

chrome/browser/resources/options/browser_options.js

 // Copyright (c) 2012 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.
 
 cr.exportPath('options');
 
 /**
  * @typedef {{actionLinkText: (string|undefined),
  *            hasError: (boolean|undefined),
  *            hasUnrecoverableError: (boolean|undefined),
@@ skipping 523 matching lines @@
       // Easy Unlock section.
       if (loadTimeData.getBoolean('easyUnlockAllowed')) {
         $('easy-unlock-section').hidden = false;
         $('easy-unlock-setup-button').onclick = function(event) {
           chrome.send('launchEasyUnlockSetup');
         };
         $('easy-unlock-turn-off-button').onclick = function(event) {
           PageManager.showPageByName('easyUnlockTurnOffOverlay');
         };
       }
+      $('easy-unlock-enable-proximity-detection').hidden =
+          !loadTimeData.getBoolean('easyUnlockProximityDetectionAllowed');
 
       // Website Settings section.
       if (loadTimeData.getBoolean('websiteSettingsManagerEnabled')) {
         $('website-settings-section').hidden = false;
         $('website-management-button').onclick = function(event) {
           PageManager.showPageByName('websiteSettings');
         };
       }
 
       // Web Content section.
@@ skipping 1588 matching lines @@
       }
       button.textContent = loadTimeData.getString(strId);
     };
   }
 
   // Export
   return {
     BrowserOptions: BrowserOptions
   };
 });