Disk cache v3 ref2

net/disk_cache/disk_format_base.h

Index: net/disk_cache/disk_format_base.h
===================================================================
--- net/disk_cache/disk_format_base.h	(revision 232523)
+++ net/disk_cache/disk_format_base.h	(working copy)
@@ -33,6 +33,7 @@
 const uint32 kBlockMagic = 0xC104CAC3;
 const int kBlockHeaderSize = 8192;  // Two pages: almost 64k entries
 const int kMaxBlocks = (kBlockHeaderSize - 80) * 8;
+const int kNumExtraBlocks = 1024;
 
 // Bitmap to track used blocks on a block-file.
 typedef uint32 AllocBitmap[kMaxBlocks / 32];
@@ -44,8 +45,12 @@
 // instance, an entry of 3 blocks is an entry of type 3. We also keep track of
 // where did we find the last entry of that type (to avoid searching the bitmap
 // from the beginning every time).
+//
+// The only difference between versions 2 and 3 is that the latter stores the
+// header and allocation file in a dedicated file, and the data in another file,
+// instead of using a single file for both things (as does version 2).
 // This Structure is the header of a block-file:
-struct BlockFileHeader {
+struct NET_EXPORT_PRIVATE BlockFileHeader {
   uint32          magic;
   uint32          version;
   int16           this_file;    // Index of this file.