Cache Backend Proxy to intercept all cache events from the IO thread.

net/disk_cache/simple/simple_disk_format.cc

 // Copyright (c) 2013 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 "net/disk_cache/simple/simple_disk_format.h"
 
 #include "base/hash.h"
 #include "base/logging.h"
 #include "base/sha1.h"
 #include "base/stringprintf.h"
 #include "base/time.h"
 
 namespace disk_cache {
 
+SimpleFileHeader::SimpleFileHeader() {
+  // Make hashing repeatable: leave no padding bytes untouched.
+  memset(this, 0, sizeof(*this));
+}
+
 std::string GetEntryHashForKey(const std::string& key) {
   const std::string sha_hash = base::SHA1HashString(key);
   const std::string key_hash = base::StringPrintf(
       "%02x%02x%02x%02x%02x",
       implicit_cast<unsigned char>(sha_hash[0]),
       implicit_cast<unsigned char>(sha_hash[1]),
       implicit_cast<unsigned char>(sha_hash[2]),
       implicit_cast<unsigned char>(sha_hash[3]),
       implicit_cast<unsigned char>(sha_hash[4]));
   DCHECK_EQ(static_cast<size_t>(kEntryHashKeySize), key_hash.size());
@@ skipping 65 matching lines @@
                           EntryMetadata* to) {
   if (to->last_used_time == 0)
     to->last_used_time = from.last_used_time;
   if (to->entry_size == 0)
     to->entry_size = from.entry_size;
 }
 
 }  // namespace SimpleIndexFile
 
 }  // namespace disk_cache