DevTools: promisify ContentProvider.requestContent and all its clients.

third_party/WebKit/Source/devtools/front_end/common/StaticContentProvider.js

 // Copyright 2014 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.
 
 /**
  * @constructor
  * @implements {WebInspector.ContentProvider}
  * @param {!WebInspector.ResourceType} contentType
  * @param {string} content
  * @param {string=} contentURL
@@ skipping 37 matching lines @@
      * @override
      * @return {!WebInspector.ResourceType}
      */
     contentType: function()
     {
         return this._contentType;
     },
 
     /**
      * @override
-     * @param {function(?string)} callback
+     * @return {!Promise<?string>}
      */
-    requestContent: function(callback)
+    requestContent: function()
     {
-        callback(this._content);
+        return Promise.resolve(/** @type {?string} */(this._content));
     },
 
     /**
      * @override
      * @param {string} query
      * @param {boolean} caseSensitive
      * @param {boolean} isRegex
      * @param {function(!Array.<!WebInspector.ContentProvider.SearchMatch>)} callback
      */
     searchInContent: function(query, caseSensitive, isRegex, callback)
     {
         WebInspector.StaticContentProvider.searchInContent(this._content, query, caseSensitive, isRegex, callback);
     }
 }