Expire appcaches that fail to update for "too long".

content/browser/appcache/appcache.h

Index: content/browser/appcache/appcache.h
diff --git a/content/browser/appcache/appcache.h b/content/browser/appcache/appcache.h
index a444579a64d04834843f916086ee99c35e7ed43b..27863ceccdc2cf39a68f75aeb782e61e3f520840 100644
--- a/content/browser/appcache/appcache.h
+++ b/content/browser/appcache/appcache.h
@@ -103,8 +103,13 @@ class CONTENT_EXPORT AppCache
     return false;
   }
 
+  // When this version was stored by an update job.
   base::Time update_time() const { return update_time_; }
 
+  // Used to evict caches that fail to update in a reasonable timeframe.
+  base::Time newest_successful_unconditional_update_check_time() { return base::Time(); }

[palmer, 2015/04/21 19:56:34]

In the real implementation, these wouldn't really be base::Time(), right? You'd
store them in fields and persist them to disk?

[michaeln, 2015/04/21 20:20:15]

Just like update_time, the value would stored on disk and the in-memory
representation would be base::Time.

+  base::Time oldest_failed_update_check_time() const; { return base::Time(); }
+
   int64 cache_size() const { return cache_size_; }
 
   void set_update_time(base::Time ticks) { update_time_ = ticks; }