Implement the content/renderer and content/browser part of the Device Motion API.

content/renderer/shared_memory_seqlock_reader_base.h

+// Copyright (c) 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_RENDERER_SHARED_MEMORY_SEQLOCK_READER_BASE_H_
+#define CONTENT_RENDERER_SHARED_MEMORY_SEQLOCK_READER_BASE_H_
+
+#include "base/shared_memory.h"
+#include "base/memory/scoped_ptr.h"
+#include "content/common/shared_memory_seqlock_buffer.h"
+
+namespace content {
+
+class SharedMemorySeqLockReaderBase  {
+ protected:
+  SharedMemorySeqLockReaderBase() { }
+  virtual ~SharedMemorySeqLockReaderBase() { }
+
+  SharedMemorySeqLockBufferBase* InitializeSharedMemory(
+      base::SharedMemoryHandle shared_memory_handle,
+      size_t buffer_size);
+
+  bool FetchFromBuffer(void* final, void* temp, void* from, size_t size);
+
+  static const int kMaximumContentionCount = 10;
+  base::SharedMemoryHandle renderer_shared_memory_handle_;
+  scoped_ptr<base::SharedMemory> renderer_shared_memory_;
+  SharedMemorySeqLockBufferBase* base_buffer_;
+};
+
+}  // namespace content
+
+#endif  // CONTENT_RENDERER_SHARED_MEMORY_SEQLOCK_READER_BASE_H_