[DevTools] Properly handle cache-only requests when cache is disabled

third_party/WebKit/public/platform/WebCachePolicy.h

 // Copyright 2016 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 WebCachePolicy_h
 #define WebCachePolicy_h
 
 namespace blink {
 
 enum class WebCachePolicy {
   UseProtocolCachePolicy,   // normal load
   ValidatingCacheData,      // reload
   BypassingCache,           // end-to-end reload
   ReturnCacheDataElseLoad,  // back/forward or encoding change - allow stale
                             // data
   ReturnCacheDataDontLoad,  // results of a post - allow stale data and only use
                             // cache
   ReturnCacheDataIfValid,   // for cache-aware loading - disallow stale data
+  BypassCacheLoadOnlyFromCache,  // for cache-only load when disable cache
+                                 // is enabled. Results in a network error.
 };
 
 }  // namespace blink
 
 #endif  // WebCachePolicy_h