Move OneWriterSeqLock and SharedMemorySeqLockBuffer from content/ to device/base/synchronization

content/common/shared_memory_seqlock_buffer.h

-// Copyright 2013 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 CONTENT_COMMON_SHARED_MEMORY_SEQLOCK_BUFFER_H_
-#define CONTENT_COMMON_SHARED_MEMORY_SEQLOCK_BUFFER_H_
-
-#include "content/common/one_writer_seqlock.h"
-
-namespace content {
-
-// This structure is stored in shared memory that's shared between the browser
-// which does the hardware polling, and the consumers of the data,
-// i.e. the renderers. The performance characteristics are that
-// we want low latency (so would like to avoid explicit communication via IPC
-// between producer and consumer) and relatively large data size.
-//
-// Writer and reader operate on the same buffer assuming contention is low, and
-// contention is detected by using the associated SeqLock.
-
-template<class Data>
-class SharedMemorySeqLockBuffer {
- public:
-  OneWriterSeqLock seqlock;
-  Data data;
-};
-
-}  // namespace content
-
-#endif  // CONTENT_COMMON_SHARED_MEMORY_SEQLOCK_BUFFER_H_