Move shared files in net/quic/ into net/quic/core/

net/quic/quic_simple_buffer_allocator.h

-// Copyright (c) 2012 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_SIMPLE_BUFFER_ALLOCATOR_H_
-#define NET_QUIC_SIMPLE_BUFFER_ALLOCATOR_H_
-
-#include "net/quic/quic_protocol.h"
-
-namespace net {
-
-class NET_EXPORT_PRIVATE SimpleBufferAllocator : public QuicBufferAllocator {
- public:
-  char* New(size_t size) override;
-  char* New(size_t size, bool flag_enable) override;
-  void Delete(char* buffer) override;
-};
-
-}  // namespace net
-
-#endif  // NET_QUIC_SIMPLE_BUFFER_ALLOCATOR_H_