Part 4.1: Is policy list subsumed under subsuming policy?

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

 /*
  * 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 348 matching lines @@
   static bool isDirectiveName(const String&);
 
   static bool isNonceableElement(const Element*);
 
   // This method checks whether the request should be allowed for an
   // experimental EmbeddingCSP feature
   // Please, see https://w3c.github.io/webappsec-csp/embedded/#origin-allowed.
   static bool shouldEnforceEmbeddersPolicy(const ResourceResponse&,
                                            SecurityOrigin*);
 
+  // This method checks if this CSP subsumes given CSP.

[Mike West, 2016/11/28 13:08:02]

Nit: "... if this policy subsumes a given policy"

Should probably also add a comment that it only works if the policy contains
only a single `CSPDirectiveList`.

+  // More information here:
+  // https://w3c.github.io/webappsec-csp/embedded/#subsume-policy
+  bool subsumes(const ContentSecurityPolicy&);
+
   Document* document() const;
 
  private:
   FRIEND_TEST_ALL_PREFIXES(ContentSecurityPolicyTest, NonceInline);
   FRIEND_TEST_ALL_PREFIXES(ContentSecurityPolicyTest, NonceSinglePolicy);
   FRIEND_TEST_ALL_PREFIXES(ContentSecurityPolicyTest, NonceMultiplePolicy);
 
   ContentSecurityPolicy();
 
   void applyPolicySideEffectsToExecutionContext();
@@ skipping 33 matching lines @@
   String m_disableEvalErrorMessage;
   WebInsecureRequestPolicy m_insecureRequestPolicy;
 
   Member<CSPSource> m_selfSource;
   String m_selfProtocol;
 };
 
 }  // namespace blink
 
 #endif