Disk Cache: Delete chained block files when they become empty....

net/disk_cache/block_files.h

Index: net/disk_cache/block_files.h
===================================================================
--- net/disk_cache/block_files.h	(revision 21550)
+++ net/disk_cache/block_files.h	(working copy)
@@ -61,6 +61,9 @@
   // Creates an empty block file and returns its index.
   int CreateNextBlockFile(FileType block_type);
 
+  // Removes a chained block file that is now empty.
+  void RemoveEmptyFile(FileType block_type);
+
   // Restores the header of a potentially inconsistent file.
   bool FixBlockFileHeader(MappedFile* file);