Rewrite scoped_ptr<T>(NULL) to use the default ctor in net/.

net/base/filter.cc

Index: net/base/filter.cc
diff --git a/net/base/filter.cc b/net/base/filter.cc
index e4dbefdd0970d7396a42c9654c2fd97fcd495c1d..36d301426f9c6b387b86b403311af656bf58864e 100644
--- a/net/base/filter.cc
+++ b/net/base/filter.cc
@@ -322,9 +322,7 @@ Filter::Filter()
       stream_buffer_size_(0),
       next_stream_data_(NULL),
       stream_data_len_(0),
-      next_filter_(NULL),
-      last_status_(FILTER_NEED_MORE_DATA) {
-}
+      last_status_(FILTER_NEED_MORE_DATA) {}
 
 Filter::FilterStatus Filter::CopyOut(char* dest_buffer, int* dest_len) {
   int out_len;