Options: Clear the 'add exception' input once an exception has been committed.

chrome/browser/resources/options/content_settings_exceptions_area.js

 // Copyright (c) 2011 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('options.contentSettings', function() {
   const InlineEditableItemList = options.InlineEditableItemList;
   const InlineEditableItem = options.InlineEditableItem;
   const ArrayDataModel = cr.ui.ArrayDataModel;
 
   /**
@@ skipping 302 matching lines @@
       return this.input.value != '';
     },
 
     /**
      * Editing is complete; update the model. As long as the pattern isn't
      * empty, we'll just add it.
      * @param {string} newPattern The pattern that the user entered.
      * @param {string} newSetting The setting the user chose.
      */
     finishEdit: function(newPattern, newSetting) {
+      this.resetInput();
       chrome.send('setException',
                   [this.contentType, this.mode, newPattern, newSetting]);
     },
   };
 
   /**
    * Creates a new exceptions list.
    * @constructor
    * @extends {cr.ui.List}
    */
@@ skipping 204 matching lines @@
     }
   };
 
   return {
     ExceptionsListItem: ExceptionsListItem,
     ExceptionsAddRowListItem: ExceptionsAddRowListItem,
     ExceptionsList: ExceptionsList,
     ContentSettingsExceptionsArea: ContentSettingsExceptionsArea,
   };
 });