RFC: use some in-memory state in SimpleCache to quickly cache-miss some CantConditionalize cases

net/disk_cache/disk_cache.cc

 // Copyright (c) 2012 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.
 
 #include <utility>
 
 #include "base/files/file_path.h"
 #include "base/macros.h"
 #include "base/metrics/field_trial.h"
 #include "base/single_thread_task_runner.h"
@@ skipping 169 matching lines @@
                        thread, net_log, backend, callback);
   return creator->Run();
 }
 
 int Backend::CalculateSizeOfEntriesBetween(base::Time initial_time,
                                            base::Time end_time,
                                            const CompletionCallback& callback) {
   return net::ERR_NOT_IMPLEMENTED;
 }
 
+uint8_t Backend::GetMemoryEntryData(const std::string& key) {
+  return 0;
+}
+
+void Backend::SetMemoryEntryData(const std::string& key, uint8_t data) {}
+
 }  // namespace disk_cache