Avoid MemoryCache eviction of preloaded resources with devtools open

third_party/WebKit/Source/core/fetch/MemoryCache.h

 /*
     Copyright (C) 1998 Lars Knoll (knoll@mpi-hd.mpg.de)
     Copyright (C) 2001 Dirk Mueller <mueller@kde.org>
     Copyright (C) 2004, 2005, 2006, 2007, 2008 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
     version 2 of the License, or (at your option) any later version.
 
@@ skipping 171 matching lines @@
   void setCapacities(size_t minDeadBytes,
                      size_t maxDeadBytes,
                      size_t totalBytes);
   void setDelayBeforeLiveDecodedPrune(double seconds) {
     m_delayBeforeLiveDecodedPrune = seconds;
   }
   void setMaxPruneDeferralDelay(double seconds) {
     m_maxPruneDeferralDelay = seconds;
   }
 
-  void evictResources();
+  enum EvictResourcePolicy { EvictAllResources, DoNotEvictUnusedPreloads };
+  void evictResources(EvictResourcePolicy = EvictAllResources);
 
   void prune();
 
   // Called to adjust a resource's size, lru list position, and access count.
   void update(Resource*,
               size_t oldSize,
               size_t newSize,
               bool wasAccessed = false);
   void updateForAccess(Resource* resource) {
     update(resource, resource->size(), resource->size(), true);
@@ skipping 106 matching lines @@
 // Returns the global cache.
 CORE_EXPORT MemoryCache* memoryCache();
 
 // Sets the global cache, used to swap in a test instance. Returns the old
 // MemoryCache object.
 CORE_EXPORT MemoryCache* replaceMemoryCacheForTesting(MemoryCache*);
 
 }  // namespace blink
 
 #endif