Add QuicStringPiece which is actually StringPiece.

net/quic/platform/impl/quic_string_piece_impl.h

Index: net/quic/platform/impl/quic_string_piece_impl.h
diff --git a/net/quic/platform/impl/quic_string_piece_impl.h b/net/quic/platform/impl/quic_string_piece_impl.h
new file mode 100644
index 0000000000000000000000000000000000000000..a5bf3fd3e781d175efd04abfbf6aa906fd3ccb8b
--- /dev/null
+++ b/net/quic/platform/impl/quic_string_piece_impl.h
@@ -0,0 +1,16 @@
+// Copyright (c) 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef NET_QUIC_PLATFORM_IMPL_QUIC_STRING_PIECE_IMPL_H_
+#define NET_QUIC_PLATFORM_IMPL_QUIC_STRING_PIECE_IMPL_H_
+
+#include "base/strings/string_piece.h"
+
+namespace net {
+
+using QuicStringPieceImpl = base::StringPiece;
+
+}  // namespace net
+
+#endif  // NET_QUIC_PLATFORM_IMPL_QUIC_STRING_PIECE_IMPL_H_