Disk Cache: Add more corruption tracking histograms.

net/disk_cache/rankings.h

Index: net/disk_cache/rankings.h
===================================================================
--- net/disk_cache/rankings.h	(revision 133063)
+++ net/disk_cache/rankings.h	(working copy)
@@ -1,4 +1,4 @@
-// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Copyright (c) 2012 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.
 
@@ -146,6 +146,11 @@
   typedef std::pair<CacheAddr, CacheRankingsBlock*> IteratorPair;
   typedef std::list<IteratorPair> IteratorList;
 
+  enum ListDirection {

[gavinp, 2012/04/26 15:46:54]

Maybe name this ForwardsOrBackwards ?

[rvargas (doing something else), 2012/04/27 00:18:10]

The name of a type should express what the type is, not what the possible values
of that type are.

I think this is you unconsciously looking for a bool :p

+    FORWARD,
+    BACKWARD
+  };
+
   void ReadHeads();
   void ReadTails();
   void WriteHead(List list);
@@ -164,10 +169,6 @@
   void FinishInsert(CacheRankingsBlock* rankings);
   void RevertRemove(CacheRankingsBlock* rankings);
 
-  // Returns false if this entry will not be recognized as dirty (called during
-  // selfcheck).
-  bool CheckEntry(CacheRankingsBlock* rankings);
-
   // Returns false if node is not properly linked. This method may change the
   // provided |list| to reflect the list where this node is actually stored.
   bool CheckLinks(CacheRankingsBlock* node, CacheRankingsBlock* prev,
@@ -180,6 +181,13 @@
   // error code (negative value).
   int CheckList(List list);
 
+  // Walks a list in the desired direction until |stop1| or |stop2| nodes are

[gavinp, 2012/04/26 15:46:54]

I like "end", as it's used in the standard library to mean the same concept a
number of times.  I don't like these number postfixes; especially since in the
same function declaration we use the same pattern of postfixing to mean two
completely different things (ordering vs alternatives).

Also, a grammar nit:
until the nodes |end| or |end_other| are reached.

+  // reached. Returns an error code (0 on success), the number of items verified
+  // and the addresses of the last nodes visited (|last2| was seen before

[gavinp, 2012/04/26 15:46:54]

how about |second_last| and |last|?

+  // |last1|).
+  int CheckListSection(List list, Addr stop1, Addr stop2, ListDirection dir,
+                       Addr* last1, Addr* last2, int* num_items);
+
   // Returns true if addr is the head or tail of any list. When there is a
   // match |list| will contain the list number for |addr|.
   bool IsHead(CacheAddr addr, List* list) const;