SimpleCache: merge the first and second stream in one file

net/disk_cache/simple/simple_entry_format.h

 // 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.
 
 #ifndef NET_DISK_CACHE_SIMPLE_SIMPLE_ENTRY_FORMAT_H_
 #define NET_DISK_CACHE_SIMPLE_SIMPLE_ENTRY_FORMAT_H_
 
 
 #include "base/basictypes.h"
 #include "base/port.h"
 #include "net/base/net_export.h"
 
 namespace base {
 class Time;
 }
 
 namespace disk_cache {
 
 const uint64 kSimpleInitialMagicNumber = GG_UINT64_C(0xfcfb6d1ba7725c30);
 const uint64 kSimpleFinalMagicNumber = GG_UINT64_C(0xf4fa6f45970d41d8);
 
-// A file in the Simple cache consists of a SimpleFileHeader followed
-// by data.
+// A file containing stream 0 and stream 1 in the Simple cache consists of:
+//   - a SimpleFileHeader.
+//   - the key.
+//   - the data from stream 1.
+//   - a SimpleFileEOF record for stream 1.
+//   - the data from stream 0.
+//   - a SimpleFileEOF record for stream 0.
 
-// A file in the Simple cache consists of:
+// A file containing stream 2 in the Simple cache consists of:
 //   - a SimpleFileHeader.
 //   - the key.
 //   - the data.
 //   - at the end, a SimpleFileEOF record.
-const uint32 kSimpleVersion = 4;
+const uint32 kSimpleVersion = 5;
 
-static const int kSimpleEntryFileCount = 3;
+static const int kSimpleEntryFileCount = 2;
+static const int kSimpleEntryStreamCount = 3;
 
 struct NET_EXPORT_PRIVATE SimpleFileHeader {
   SimpleFileHeader();
 
   uint64 initial_magic_number;
   uint32 version;
   uint32 key_length;
   uint32 key_hash;
 };
 
 struct SimpleFileEOF {
   enum Flags {
     FLAG_HAS_CRC32 = (1U << 0),
   };
 
   SimpleFileEOF();
 
   uint64 final_magic_number;
   uint32 flags;
   uint32 data_crc32;
+  // |stream_size| is only used in the EOF record for stream 0.
+  uint32 stream_size;
 };
 
 }  // namespace disk_cache
 
 #endif  // NET_DISK_CACHE_SIMPLE_SIMPLE_ENTRY_FORMAT_H_