Actually handle the Vary header in blink, rather than punting on sight.

third_party/WebKit/Source/platform/loader/fetch/Resource.h

 /*
     Copyright (C) 1998 Lars Knoll (knoll@mpi-hd.mpg.de)
     Copyright (C) 2001 Dirk Mueller <mueller@kde.org>
     Copyright (C) 2006 Samuel Weinig (sam.weinig@gmail.com)
     Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All
     rights reserved.
 
     This library is free software; you can redistribute it and/or
     modify it under the terms of the GNU Library General Public
     License as published by the Free Software Foundation; either
@@ skipping 246 matching lines @@
   void decreasePreloadCount() {
     DCHECK(m_preloadCount);
     --m_preloadCount;
   }
 
   bool canReuseRedirectChain() const;
   bool mustRevalidateDueToCacheHeaders() const;
   bool canUseCacheValidator() const;
   bool isCacheValidator() const { return m_isRevalidating; }
   bool hasCacheControlNoStoreHeader() const;
-  bool hasVaryHeader() const;
+  bool mustReloadDueToVaryHeader(const ResourceRequest& newRequest) const;
 
   bool isEligibleForIntegrityCheck(SecurityOrigin*) const;
 
   void setIntegrityMetadata(const IntegrityMetadataSet& metadata) {
     m_integrityMetadata = metadata;
   }
   const IntegrityMetadataSet& integrityMetadata() const {
     return m_integrityMetadata;
   }
   // The argument must never be |NotChecked|.
@@ skipping 224 matching lines @@
 };
 
 #define DEFINE_RESOURCE_TYPE_CASTS(typeName)                   \
   DEFINE_TYPE_CASTS(typeName##Resource, Resource, resource,    \
                     resource->getType() == Resource::typeName, \
                     resource.getType() == Resource::typeName);
 
 }  // namespace blink
 
 #endif