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

net/cookies/cookie_options.h

Index: net/cookies/cookie_options.h
diff --git a/net/cookies/cookie_options.h b/net/cookies/cookie_options.h
index 1162c96f1d2d036a65e9e6f548ea1697e345e15d..041713b6fda8a9016e7bc54719dfb5c2092ede0d 100644
--- a/net/cookies/cookie_options.h
+++ b/net/cookies/cookie_options.h
@@ -33,9 +33,6 @@ class NET_EXPORT CookieOptions {
   void set_include_first_party_only() { include_first_party_only_ = true; }
   bool include_first_party_only() const { return include_first_party_only_; }
 
-  void set_first_party(const url::Origin& origin) { first_party_ = origin; }
-  const url::Origin& first_party() const { return first_party_; }
-
   // TODO(estark): Remove once we decide whether to ship cookie
   // prefixes. https://crbug.com/541511
   void set_enforce_prefixes() { enforce_prefixes_ = true; }
@@ -53,7 +50,6 @@ class NET_EXPORT CookieOptions {
  private:
   bool exclude_httponly_;
   bool include_first_party_only_;
-  url::Origin first_party_;
   bool enforce_prefixes_;
   base::Time server_time_;
 };