Add SimpleCache index file heuristics

net/disk_cache/simple/simple_index_file.h

Index: net/disk_cache/simple/simple_index_file.h
diff --git a/net/disk_cache/simple/simple_index_file.h b/net/disk_cache/simple/simple_index_file.h
index 00141634376e3fd3ef1df66c5033f3ba255473ff..744cdf057976c868c49695349a744445a1485f8d 100644
--- a/net/disk_cache/simple/simple_index_file.h
+++ b/net/disk_cache/simple/simple_index_file.h
@@ -68,6 +68,10 @@ class NET_EXPORT_PRIVATE SimpleIndexFile {
   static void WriteToDisk(const base::FilePath& index_filename,
                           const Pickle& pickle);
 
+  // Using mtime of the file and the path, it detects if the index file is

[gavinp, 2013/04/19 11:30:17]

// Using the mtime of the file and its mtime, detects if the index file is
stale.

[felipeg, 2013/04/19 12:20:29]

Done.

+  // stale.
+  static bool IsIndexFileStale(const base::FilePath& index_filename);
+
  private:
   FRIEND_TEST_ALL_PREFIXES(SimpleIndexFileTest, Serialize);