Part 2.1: Is policy list subsumed under subsuming policy?

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

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CSPSource_h
 #define CSPSource_h
 
 #include "core/CoreExport.h"
 #include "core/frame/csp/ContentSecurityPolicy.h"
 #include "platform/heap/Handle.h"
@@ skipping 17 matching lines @@
             const String& path,
             WildcardDisposition hostWildcard,
             WildcardDisposition portWildcard);
   bool matches(const KURL&,
                ResourceRequest::RedirectStatus =
                    ResourceRequest::RedirectStatus::NoRedirect) const;
 
   // Returns true if this CSPSource subsumes the other, as defined by the
   // algorithm at https://w3c.github.io/webappsec-csp/embedded/#subsume-policy
   bool subsumes(CSPSource*);
+  // Retrieve the most restrictive information from the two CSPSources if
+  // isSimilar is true for the two. Otherwise, return nullptr.
+  CSPSource* intersect(CSPSource*);
 
   DECLARE_TRACE();
 
  private:
+  FRIEND_TEST_ALL_PREFIXES(CSPSourceTest, IsSimilar);
+  FRIEND_TEST_ALL_PREFIXES(SourceListDirectiveTest, GetIntersectCSPSources);
+
   bool schemeMatches(const String&) const;
   bool hostMatches(const String&) const;
   bool pathMatches(const String&) const;
   // Protocol is necessary to determine default port if it is zero.
   bool portMatches(int port, const String& protocol) const;
   bool isSchemeOnly() const;
+  bool isSimilar(CSPSource* other);
 
   Member<ContentSecurityPolicy> m_policy;
   String m_scheme;
   String m_host;
   int m_port;
   String m_path;
 
   WildcardDisposition m_hostWildcard;
   WildcardDisposition m_portWildcard;
 };
 
 }  // namespace blink
 
 #endif