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

device/base/synchronization/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 DEVICE_BASE_SYNCHRONIZATION_SHARED_MEMORY_SEQLOCK_BUFFER_H_
 #define DEVICE_BASE_SYNCHRONIZATION_SHARED_MEMORY_SEQLOCK_BUFFER_H_
 
 #include "device/base/synchronization/one_writer_seqlock.h"
 
 namespace device {
 
 // 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 device
 
-#endif  // DEVICE_CORE_SHARED_MEMORY_SEQLOCK_BUFFER_H_
+#endif  // DEVICE_BASE_SYNCHRONIZATION_SHARED_MEMORY_SEQLOCK_BUFFER_H_