Remove void** from disk_cache interface.

net/disk_cache/blockfile/backend_impl.cc

Index: net/disk_cache/blockfile/backend_impl.cc
diff --git a/net/disk_cache/blockfile/backend_impl.cc b/net/disk_cache/blockfile/backend_impl.cc
index c38b2bb9e33b49fa7e4945edc7380b235b5d3b8a..c3ad6e253762c8456426f5af44c1b29c23e36ed3 100644
--- a/net/disk_cache/blockfile/backend_impl.cc
+++ b/net/disk_cache/blockfile/backend_impl.cc
@@ -1250,16 +1250,35 @@ int BackendImpl::DoomEntriesSince(const base::Time initial_time,
   return net::ERR_IO_PENDING;
 }
 
-int BackendImpl::OpenNextEntry(void** iter, Entry** next_entry,
+int BackendImpl::OpenNextEntry(Iterator* iter, Entry** next_entry,
                                const CompletionCallback& callback) {
+  // TODO(gavinp): Remove all void** iter from cache.
   DCHECK(!callback.is_null());
-  background_queue_.OpenNextEntry(iter, next_entry, callback);
-  return net::ERR_IO_PENDING;
-}
 
-void BackendImpl::EndEnumeration(void** iter) {
-  background_queue_.EndEnumeration(*iter);
-  *iter = NULL;
+  class State : public EnumerationState {
+   public:
+    explicit State(base::WeakPtr<InFlightBackendIO> background_queue)
+        : background_queue_(background_queue),
+        data_(NULL) {}
+
+    virtual ~State() {
+      if (background_queue_)
+        background_queue_->EndEnumeration(*data());
+    }
+
+    void** data() { return &data_; }
+
+   private:
+    base::WeakPtr<InFlightBackendIO> background_queue_;
+    void* data_;
+  };
+
+  if (!*iter)
+    iter->reset(new State(GetBackgroundQueue()));
+  State* state = static_cast<State*>(iter->get());
+
+  background_queue_.OpenNextEntry(state->data(), next_entry, callback);
+  return net::ERR_IO_PENDING;
 }
 
 void BackendImpl::GetStats(StatsItems* stats) {