[WIP] make GURL::path() return a StringPiece

ios/web/public/test/http_server.mm

Index: ios/web/public/test/http_server.mm
diff --git a/ios/web/public/test/http_server.mm b/ios/web/public/test/http_server.mm
index e733a5f8b5c342f90dd3b2b7879daea26273aeb6..7b6335d924e64975fec1eb91079d18fe5cc806a7 100644
--- a/ios/web/public/test/http_server.mm
+++ b/ios/web/public/test/http_server.mm
@@ -168,7 +168,8 @@ GURL HttpServer::MakeUrlForHttpServer(const std::string& url) const {
 
   // It is necessary to prepend the host of the input URL so that URLs such
   // as http://origin/foo, http://destination/foo can be disamgiguated.
-  const std::string new_path = std::string(result.host() + result.path());
+  const std::string new_path =
+      std::string(result.host() + result.path().as_string());
   replacements.SetPathStr(new_path);
 
   return result.ReplaceComponents(replacements);