Remove various 'using std::' statements from QUIC code and use

net/quic/core/frames/quic_padding_frame.cc

Index: net/quic/core/frames/quic_padding_frame.cc
diff --git a/net/quic/core/frames/quic_padding_frame.cc b/net/quic/core/frames/quic_padding_frame.cc
index 0f15af1f51e6782a68e6a78ac87885bb5ddfa324..99bc46862ead9c8d542df3136ceb7fef706180a1 100644
--- a/net/quic/core/frames/quic_padding_frame.cc
+++ b/net/quic/core/frames/quic_padding_frame.cc
@@ -4,12 +4,12 @@
 
 #include "net/quic/core/frames/quic_padding_frame.h"
 
-using std::ostream;
 using std::string;
 
 namespace net {
 
-ostream& operator<<(ostream& os, const QuicPaddingFrame& padding_frame) {
+std::ostream& operator<<(std::ostream& os,
+                         const QuicPaddingFrame& padding_frame) {
   os << "{ num_padding_bytes: " << padding_frame.num_padding_bytes << " }\n";
   return os;
 }