Add quic_stack_trace.

net/quic/platform/impl/quic_stack_trace_impl.h

+// 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_STACK_TRACE_IMPL_H_
+#define NET_QUIC_PLATFORM_IMPL_QUIC_STACK_TRACE_IMPL_H_
+
+#include "base/debug/stack_trace.h"
+
+namespace net {
+
+inline std::string QuicStackTraceImpl() {
+  return base::debug::StackTrace().ToString();
+}
+
+}  // namespace net
+
+#endif  // NET_QUIC_PLATFORM_IMPL_QUIC_STACK_TRACE_IMPL_H_