DevTools: promisify ContentProvider.requestContent and all its clients.

third_party/WebKit/Source/devtools/front_end/snippets/ScriptSnippetModel.js

 /*
  * Copyright (C) 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 535 matching lines @@
      * @override
      * @return {!WebInspector.ResourceType}
      */
     contentType: function()
     {
         return WebInspector.resourceTypes.Script;
     },
 
     /**
      * @override
-     * @param {function(?string)} callback
+     * @return {!Promise<?string>}
      */
-    requestContent: function(callback)
+    requestContent: function()
     {
-        callback(this._snippet.content);
+        return Promise.resolve(/** @type {?string} */(this._snippet.content));
     },
 
     /**
      * @override
      * @param {string} query
      * @param {boolean} caseSensitive
      * @param {boolean} isRegex
      * @param {function(!Array.<!WebInspector.ContentProvider.SearchMatch>)} callback
      */
     searchInContent: function(query, caseSensitive, isRegex, callback)
@@ skipping 96 matching lines @@
         this._model.deleteScriptSnippet(url);
     },
 
     __proto__: WebInspector.ContentProviderBasedProject.prototype
 }
 
 /**
  * @type {!WebInspector.ScriptSnippetModel}
  */
 WebInspector.scriptSnippetModel = new WebInspector.ScriptSnippetModel(WebInspector.workspace);