[MD History] Disable Clear Browsing Data button for supervised users.

chrome/browser/resources/md_history/list_container.js

 // Copyright 2016 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.
 
 Polymer({
   is: 'history-list-container',
 
   properties: {
+    canDeleteHistory_: {
+      type: Boolean,
+      value: loadTimeData.getBoolean('allowDeletingHistory'),
+    },
+
     /** @type {!QueryState} */
     queryState: Object,
 
     /** @type {!QueryResult} */
     queryResult: Object,
 
     /**
      * @private {?{
      *   index: number,
      *   item: !HistoryEntry,
@@ skipping 184 matching lines @@
     this.closeMenu_();
   },
 
   /**
    * @return {Element}
    * @private
    */
   getSelectedList_: function() {
     return this.$['infinite-list'];
   },
-
-  /** @private */
-  canDeleteHistory_: function() {
-    return loadTimeData.getBoolean('allowDeletingHistory');
-  }
 });