Add support for 'start_url' in Manifest.

content/renderer/manifest/manifest_parser.h

 // 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.
 
 #ifndef CONTENT_RENDERER_MANIFEST_MANIFEST_PARSER_H_
 #define CONTENT_RENDERER_MANIFEST_MANIFEST_PARSER_H_
 
 #include "base/strings/string_piece.h"
 #include "content/common/content_export.h"
 
+class GURL;
+
 namespace base {
 class DictionaryValue;
 }
 
 namespace content {
 
 struct Manifest;
 
 // ManifestParser handles the logic of parsing the Web Manifest from a string.
 // It implements:
 // http://w3c.github.io/manifest/#dfn-steps-for-processing-a-manifest
 class CONTENT_EXPORT ManifestParser {
  public:
-  static Manifest Parse(const base::StringPiece&);
+  static Manifest Parse(const base::StringPiece&,
+                        const GURL& manifest_url,
+                        const GURL& document_url);
 };
 
 } // namespace content
 
 #endif // CONTENT_RENDERER_MANIFEST_MANIFEST_PARSER_H_