DevTools: promisify ContentProvider.requestContent and all its clients.

third_party/WebKit/Source/devtools/front_end/common/ContentProvider.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 27 matching lines @@
      * @return {string}
      */
     contentURL: function() { },
 
     /**
      * @return {!WebInspector.ResourceType}
      */
     contentType: function() { },
 
     /**
-     * @param {function(?string)} callback
+     * @return {!Promise<?string>}
      */
-    requestContent: function(callback) { },
+    requestContent: function() { },
 
     /**
      * @param {string} query
      * @param {boolean} caseSensitive
      * @param {boolean} isRegex
      * @param {function(!Array.<!WebInspector.ContentProvider.SearchMatch>)} callback
      */
     searchInContent: function(query, caseSensitive, isRegex, callback) { }
 }
 
@@ skipping 21 matching lines @@
     var contentString = new String(content);
     var result = [];
     for (var i = 0; i < contentString.lineCount(); ++i) {
         var lineContent = contentString.lineAt(i);
         regex.lastIndex = 0;
         if (regex.exec(lineContent))
             result.push(new WebInspector.ContentProvider.SearchMatch(i, lineContent));
     }
     return result;
 }