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..0bbe3e370c8744c07a5cdf6ca8153b3df74835c8 100644
--- a/net/disk_cache/blockfile/backend_impl.cc
+++ b/net/disk_cache/blockfile/backend_impl.cc
@@ -1250,16 +1250,29 @@ int BackendImpl::DoomEntriesSince(const base::Time initial_time,
   return net::ERR_IO_PENDING;
 }
 
-int BackendImpl::OpenNextEntry(void** iter, Entry** next_entry,
-                               const CompletionCallback& callback) {
-  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;
+scoped_ptr<Backend::Iterator> BackendImpl::CreateIterator() {
+  class BackendIterator : public Backend::Iterator {
+   public:
+    explicit BackendIterator(base::WeakPtr<InFlightBackendIO> background_queue)
+        : background_queue_(background_queue), data_(NULL) {}
+
+    virtual int OpenNextEntry(
+        Entry** next_entry,
+        const net::CompletionCallback& callback) OVERRIDE {
+      if (!background_queue_)
+        return net::ERR_FAILED;
+      background_queue_->OpenNextEntry(&data_, next_entry, callback);
+      return net::ERR_IO_PENDING;
+    }
+
+   private:
+    const base::WeakPtr<InFlightBackendIO> background_queue_;
+    void* data_;
+  };
+
+  return
+      scoped_ptr<Backend::Iterator>(new BackendIterator(GetBackgroundQueue()));
 }
 
 void BackendImpl::GetStats(StatsItems* stats) {