Delete enumerations at Simple Cache backend deletion.

net/disk_cache/simple/simple_backend_impl.h

Index: net/disk_cache/simple/simple_backend_impl.h
diff --git a/net/disk_cache/simple/simple_backend_impl.h b/net/disk_cache/simple/simple_backend_impl.h
index 2bd00818b9cfb1f550f432f9f53521b41b66f049..8f5f02df94f194a7d680fe3e8880a43c5ba057c0 100644
--- a/net/disk_cache/simple/simple_backend_impl.h
+++ b/net/disk_cache/simple/simple_backend_impl.h
@@ -13,6 +13,7 @@
 #include "base/compiler_specific.h"
 #include "base/containers/hash_tables.h"
 #include "base/files/file_path.h"
+#include "base/id_map.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
@@ -107,6 +108,8 @@ class NET_EXPORT_PRIVATE SimpleBackendImpl : public Backend,
  private:
   typedef base::hash_map<uint64, SimpleEntryImpl*> EntryMap;
 
+  typedef IDMap<std::vector<uint64>, IDMapOwnPointer> ActiveEnumerationMap;
+
   typedef base::Callback<void(base::Time mtime, uint64 max_size, int result)>
       InitializeIndexCallback;
 
@@ -206,6 +209,9 @@ class NET_EXPORT_PRIVATE SimpleBackendImpl : public Backend,
 
   EntryMap active_entries_;
 
+  // One entry for every enumeration in progress.
+  ActiveEnumerationMap active_enumerations_;
+
   // The set of all entries which are currently being doomed. To avoid races,
   // these entries cannot have Doom/Create/Open operations run until the doom
   // is complete. The base::Closure map target is used to store deferred