Add QuicStringPiece which is actually StringPiece.

net/quic/test_tools/quic_stream_peer.cc

Index: net/quic/test_tools/quic_stream_peer.cc
diff --git a/net/quic/test_tools/quic_stream_peer.cc b/net/quic/test_tools/quic_stream_peer.cc
index 859bc6ac50cf0a7ec5c9bad956af17b51934b326..7b79cb3c8ec476573fb7f366950548b05d05ac45 100644
--- a/net/quic/test_tools/quic_stream_peer.cc
+++ b/net/quic/test_tools/quic_stream_peer.cc
@@ -8,8 +8,6 @@
 
 #include "net/quic/core/quic_stream.h"
 
-using base::StringPiece;
-
 namespace net {
 namespace test {
 
@@ -66,7 +64,7 @@ bool QuicStreamPeer::StreamContributesToConnectionFlowControl(
 // static
 void QuicStreamPeer::WriteOrBufferData(
     QuicStream* stream,
-    StringPiece data,
+    QuicStringPiece data,
     bool fin,
     QuicReferenceCountedPointer<QuicAckListenerInterface> ack_listener) {
   stream->WriteOrBufferData(data, fin, std::move(ack_listener));