[Favicon] Add new fallback icon rendering flow.

chrome/common/favicon/favicon_url_parser.h

Index: chrome/common/favicon/favicon_url_parser.h
diff --git a/chrome/common/favicon/favicon_url_parser.h b/chrome/common/favicon/favicon_url_parser.h
index d7de77080a89e455c09ee6dbc8e18becba9fd981..e9c86b162cb3e9dce22e87aaff66e32c894f5b3d 100644
--- a/chrome/common/favicon/favicon_url_parser.h
+++ b/chrome/common/favicon/favicon_url_parser.h
@@ -5,8 +5,12 @@
 #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 {
@@ -22,6 +26,10 @@ struct ParsedFaviconPath {
   // 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;