Remove <iostream> where possible.

net/tools/flip_server/balsa_headers.cc

Index: net/tools/flip_server/balsa_headers.cc
diff --git a/net/tools/flip_server/balsa_headers.cc b/net/tools/flip_server/balsa_headers.cc
index 56a83a2c3c2f878273c3f36f81078cfbf9fb955c..b58fb032a01f9ddd239ca5fedd805eef810e7862 100644
--- a/net/tools/flip_server/balsa_headers.cc
+++ b/net/tools/flip_server/balsa_headers.cc
@@ -71,6 +71,12 @@ namespace net {
 
 const size_t BalsaBuffer::kDefaultBlocksize;
 
+std::ostream& BalsaHeaders::iterator_base::operator<<(std::ostream& os,
+                                                      const iterator_base& it) {
+   os << "[" << it.headers_ << ", " << it.idx_ << "]";
+   return os;
+ }
+
 void BalsaHeaders::Clear() {
   balsa_buffer_.Clear();
   transfer_encoding_is_chunked_ = false;