[MD Extensions] Include the manifest code snippet in load errors

chrome/test/data/webui/extensions/extension_load_error_test.js

 // Copyright 2017 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.
 
 /** @fileoverview Suite of tests for extension-load-error. */
 cr.define('extension_load_error_tests', function() {
   /** @enum {string} */
   var TestNames = {
     Interaction: 'Interaction',
+    CodeSection: 'Code Section',
   };
 
   /**
    * @implements {extensions.LoadErrorDelegate}
    * @extends {extension_test_util.ClickMock}
    * @constructor
    */
   function MockDelegate() {}
 
   MockDelegate.prototype = {
@@ skipping 31 matching lines @@
         expectTrue(isDialogVisible());
 
         mockDelegate.testClickingCalls(
             loadError.$$('#retry'), 'retryLoadUnpacked', []);
         expectFalse(isDialogVisible());
 
         loadError.show();
         MockInteractions.tap(loadError.$$('#dismiss'));
         expectFalse(isDialogVisible());
       });
+
+      test(assert(TestNames.CodeSection), function() {
+        expectTrue(loadError.$.code.isEmpty());
+        var loadErrorProperties = {
+          error: 'Some error',
+          path: '/some/path',
+          source: {
+            beforeHighlight: 'before',
+            highlight: 'highlight',
+            afterHighlight: 'after',
+          },
+        };
+
+        loadError.set('loadError', loadErrorProperties);
+        expectFalse(loadError.$.code.isEmpty());
+      });
     });
   }
 
   return {
     registerTests: registerTests,
     TestNames: TestNames,
   };
 });