Teach URLRequest about initiator checks for First-Party-Only cookies.

net/url_request/url_request.cc

Index: net/url_request/url_request.cc
diff --git a/net/url_request/url_request.cc b/net/url_request/url_request.cc
index ad399b9ea081c51ed85b81c790be9b1215964550..c278761f6da28af4ce86b306b69887ce37c55c54 100644
--- a/net/url_request/url_request.cc
+++ b/net/url_request/url_request.cc
@@ -463,11 +463,21 @@ void URLRequest::set_first_party_url_policy(
   first_party_url_policy_ = first_party_url_policy;
 }
 
+void URLRequest::set_initiator(const url::Origin& initiator) {
+  DCHECK(!is_pending_);
+  initiator_ = initiator;
+}
+
 void URLRequest::set_method(const std::string& method) {
   DCHECK(!is_pending_);
   method_ = method;
 }
 
+bool URLRequest::IsMethodSafe() const {
+  return method_ == "GET" || method_ == "HEAD" || method_ == "OPTIONS" ||
+         method_ == "TRACE";
+}
+
 void URLRequest::SetReferrer(const std::string& referrer) {
   DCHECK(!is_pending_);
   GURL referrer_url(referrer);