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

net/cookies/canonical_cookie.cc

Index: net/cookies/canonical_cookie.cc
diff --git a/net/cookies/canonical_cookie.cc b/net/cookies/canonical_cookie.cc
index a37944b4aa34d2c64415e8747285913fb11598f3..91107e3aafc1116379d86a03bc398cc8287261a4 100644
--- a/net/cookies/canonical_cookie.cc
+++ b/net/cookies/canonical_cookie.cc
@@ -390,15 +390,9 @@ bool CanonicalCookie::IncludeForRequestURL(const GURL& url,
   // match the cookie-path.
   if (!IsOnPath(url.path()))
     return false;
-
-  // Include first-party-only cookies if:
-  //
-  // * |options| tells us to include all of them
-  // * a first-party origin is set, and they matches the origin of |url|
-  if (IsFirstPartyOnly() && !options.include_first_party_only() &&
-      !options.first_party().IsSameOriginWith(url::Origin(url))) {
+  // Don't include first-party-only cookies for non-first-party requests.
+  if (IsFirstPartyOnly() && !options.include_first_party_only_cookies())
     return false;
-  }
 
   return true;
 }