Part 2.1: Is policy list subsumed under subsuming policy?

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

Index: third_party/WebKit/Source/core/frame/csp/SourceListDirective.h
diff --git a/third_party/WebKit/Source/core/frame/csp/SourceListDirective.h b/third_party/WebKit/Source/core/frame/csp/SourceListDirective.h
index 38752daecb9163b5dc885ed101e7156d0cc3930e..11443b2302692c0c5311b7afed126bfc6ecf3fb3 100644
--- a/third_party/WebKit/Source/core/frame/csp/SourceListDirective.h
+++ b/third_party/WebKit/Source/core/frame/csp/SourceListDirective.h
@@ -47,6 +47,8 @@ class CORE_EXPORT SourceListDirective final : public CSPDirective {
   uint8_t hashAlgorithmsUsed() const;
 
  private:
+  FRIEND_TEST_ALL_PREFIXES(SourceListDirectiveTest, GetNormalizedCSPSources);
+
   bool parseSource(const UChar* begin,
                    const UChar* end,
                    String& scheme,
@@ -82,6 +84,8 @@ class CORE_EXPORT SourceListDirective final : public CSPDirective {
                      const DigestValue& hash);
 
   bool hasSourceMatchInList(const KURL&, ResourceRequest::RedirectStatus) const;
+  HeapVector<Member<CSPSource>> getNormalizedCSPSources(
+      HeapVector<Member<CSPSource>> other);
 
   Member<ContentSecurityPolicy> m_policy;
   HeapVector<Member<CSPSource>> m_list;