Part 4.1: Is policy list subsumed under subsuming policy?

third_party/WebKit/Source/core/frame/csp/ContentSecurityPolicy.cpp

 /*
  * Copyright (C) 2011 Google, Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 1577 matching lines @@
   if (name == "treat-as-public-address")
     return DirectiveType::TreatAsPublicAddress;
   if (name == "upgrade-insecure-requests")
     return DirectiveType::UpgradeInsecureRequests;
   if (name == "worker-src")
     return DirectiveType::WorkerSrc;
 
   return DirectiveType::Undefined;
 }
 
+bool ContentSecurityPolicy::subsumes(const ContentSecurityPolicy& other) {
+  if (!m_policies.size() || !other.m_policies.size())
+    return !m_policies.size();
+  // Embedding-CSP must specify only one policy.
+  if (m_policies.size() != 1)
+    return false;
+
+  CSPDirectiveListVector otherVector;
+  for (const auto& policy : other.m_policies) {
+    if (!policy->isReportOnly())
+      otherVector.append(policy);
+  }
+
+  return m_policies[0]->subsumes(otherVector);
+}
+
 }  // namespace blink