Change bookmarkManager API from experimental to private.

chrome/browser/resources/bookmark_manager/js/bmm.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.define('bmm', function() {
   const Promise = cr.Promise;
 
   /**
    * Whether a node contains another node.
    * @param {!BookmarkTreeNode} parent
@@ skipping 23 matching lines @@
   /**
    * Loads a subtree of the bookmark tree and returns a {@code cr.Promise} that
    * will be fulfilled when done. This reuses multiple loads so that we do not
    * load the same subtree more than once at the same time.
    * @return {!cr.Promise} The future promise for the load.
    */
   function loadSubtree(id) {
     var p = new Promise;
     if (!(id in loadingPromises)) {
       loadingPromises[id] = new Promise;
-      chrome.experimental.bookmarkManager.getSubtree(id, false,
-                                                     function(nodes) {
+      chrome.bookmarkManagerPrivate.getSubtree(id, false, function(nodes) {
         loadingPromises[id].value = nodes && nodes[0];
         delete loadingPromises[id];
       });
     }
     loadingPromises[id].addListener(function(n) {
       p.value = n;
     });
     return p;
   }
 
@@ skipping 166 matching lines @@
   };
 
   return {
     contains: contains,
     isFolder: isFolder,
     loadSubtree: loadSubtree,
     loadTree: loadTree,
     addBookmarkModelListeners: addBookmarkModelListeners
   };
 });