Remove <iostream> where possible.

net/tools/flip_server/balsa_headers.h

Index: net/tools/flip_server/balsa_headers.h
diff --git a/net/tools/flip_server/balsa_headers.h b/net/tools/flip_server/balsa_headers.h
index 4f530c704837031ef940712a02821fea4a055a30..24e794083f1cd05f5d6c77b23ca68f29f3809a73 100644
--- a/net/tools/flip_server/balsa_headers.h
+++ b/net/tools/flip_server/balsa_headers.h
@@ -6,7 +6,7 @@
 #define NET_TOOLS_FLIP_SERVER_BALSA_HEADERS_H_
 
 #include <algorithm>
-#include <iostream>
+#include <iosfwd>
 #include <iterator>
 #include <string>
 #include <utility>
@@ -470,10 +470,7 @@ class BalsaHeaders {
     // operator<< work for the classes it sees.  It would be better if there
     // was an additional traits-like system for the gUnit output... but oh
     // well.
-    friend std::ostream& operator<<(std::ostream& os, const iterator_base& it) {
-      os << "[" << it.headers_ << ", " << it.idx_ << "]";
-      return os;
-    }
+    std::ostream& operator<<(std::ostream& os, const iterator_base& it);
 
    protected:
     iterator_base(const BalsaHeaders* headers, HeaderLines::size_type index) :