Do not initiate revalidation of Resource with redirects from MemoryCache

third_party/WebKit/Source/core/fetch/Resource.cpp

 /*
     Copyright (C) 1998 Lars Knoll (knoll@mpi-hd.mpg.de)
     Copyright (C) 2001 Dirk Mueller (mueller@kde.org)
     Copyright (C) 2002 Waldo Bastian (bastian@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 942 matching lines @@
     return !canUseResponse(m_response, m_responseTimestamp) || m_resourceRequest.cacheControlContainsNoCache() || m_resourceRequest.cacheControlContainsNoStore();
 }
 
 bool Resource::canUseCacheValidator()
 {
     if (isLoading() || errorOccurred())
         return false;
 
     if (hasCacheControlNoStoreHeader())
         return false;
+
+    // Do not revalidate Resource with redirects. https://crbug.com/613971
+    if (!redirectChain().isEmpty())

[Nate Chapin, 2016/05/27 17:00:57]

How does this interact with canReuseRedirectChain()?

[hiroshige, 2016/05/30 06:28:50]

This CL prohibits |Revalidate| for Resource with redirects, but not |Use| for
such a Resource.
Therefore, canReuseRedirectChain() still can return true for Resource with
redirects (meaning "we can |Use|"), while canUseCacheValidator() always returns
false (meaning "we cannot |Revalidate|").
In such case,
- We can |Use| the Resource without revalidating (when other conditions met).
- We can NOT |Revalidate| the Resource, because of Chromium/Blink's
implementation.
- We can |Reload| the Resource.

+        return false;
+
     return m_response.hasCacheValidatorFields() || m_resourceRequest.hasCacheValidatorFields();
 }
 
 bool Resource::isPurgeable() const
 {
     return m_data && !m_data->isLocked();
 }
 
 bool Resource::lock()
 {
@@ skipping 149 matching lines @@
     case Resource::Media:
         return "Media";
     case Resource::Manifest:
         return "Manifest";
     }
     ASSERT_NOT_REACHED();
     return "Unknown";
 }
 
 } // namespace blink