[Favicon] Add new fallback icon rendering flow.

chrome/common/favicon/favicon_url_parser.h

 // Copyright 2013 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 CHROME_COMMON_FAVICON_FAVICON_URL_PARSER_H_
 #define CHROME_COMMON_FAVICON_FAVICON_URL_PARSER_H_
 
+#include <memory>
 #include <string>
 
+#include "components/favicon_base/fallback_icon_specs_builder.h"
+#include "third_party/skia/include/core/SkColor.h"
+
 namespace chrome {
 
 struct ParsedFaviconPath {
   // Whether the URL has the "iconurl" parameter.
   bool is_icon_url;
 
   // The URL from which the favicon is being requested.
   std::string url;
 
   // The size of the requested favicon in dip.
   int size_in_dip;
 
   // The device scale factor of the requested favicon.
   float device_scale_factor;
 
+  // Specifications of fallback icon. This is nullptr if no fallback.
+  std::unique_ptr<favicon_base::FallbackIconSpecsBuilder>
+      fallback_specs_builder;
+
   // The index of the first character (relative to the path) where the the URL
   // from which the favicon is being requested is located.
   size_t path_index;
 };
 
 // Parses |path|, which should be in the format described at the top of the
 // file "chrome/browser/ui/webui/favicon_source.h". |icon_types| indicates
 // which icon types are supported. Returns true if |path| could be parsed.
 // The result of the parsing will be stored in a ParsedFaviconPath struct.
 bool ParseFaviconPath(const std::string& path,
                       int icon_types,
                       ParsedFaviconPath* parsed);
 
 }  // namespace chrome
 
 #endif  // CHROME_COMMON_FAVICON_FAVICON_URL_PARSER_H_