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

content/browser/frame_host/frame_tree_node.h

Index: content/browser/frame_host/frame_tree_node.h
diff --git a/content/browser/frame_host/frame_tree_node.h b/content/browser/frame_host/frame_tree_node.h
index df18cf15ee93d96b4e2e3223710f36c974448c19..9103b63aa7055e10c6add231ed9ec90bf1b3fb1b 100644
--- a/content/browser/frame_host/frame_tree_node.h
+++ b/content/browser/frame_host/frame_tree_node.h
@@ -97,6 +97,8 @@ class CONTENT_EXPORT FrameTreeNode {
     return replication_state_.name;
   }
 
+  const url::Origin& frame_origin() const { return replication_state_.origin; }
+
   size_t child_count() const {
     return children_.size();
   }