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

content/renderer/shared_memory_seqlock_reader.cc

 // 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.
 
 #include "content/renderer/shared_memory_seqlock_reader.h"
 
 namespace content {
 namespace internal {
 
 SharedMemorySeqLockReaderBase::SharedMemorySeqLockReaderBase() { }
 
 SharedMemorySeqLockReaderBase::~SharedMemorySeqLockReaderBase() { }
 
 void*
 SharedMemorySeqLockReaderBase::InitializeSharedMemory(
     base::SharedMemoryHandle shared_memory_handle, size_t buffer_size) {
   renderer_shared_memory_handle_ = shared_memory_handle;
   if (!base::SharedMemory::IsHandleValid(renderer_shared_memory_handle_))
     return 0;
   renderer_shared_memory_.reset(new base::SharedMemory(
       renderer_shared_memory_handle_, true));
 
   return (renderer_shared_memory_->Map(buffer_size))
       ? renderer_shared_memory_->memory()
       : 0;
 }
 
 bool SharedMemorySeqLockReaderBase::FetchFromBuffer(
-    content::OneWriterSeqLock* seqlock, void* final, void* temp, void* from,
+    base::OneWriterSeqLock* seqlock,
+    void* final,
+    void* temp,
+    void* from,
     size_t size) {
-
   if (!base::SharedMemory::IsHandleValid(renderer_shared_memory_handle_))
     return false;
 
   // Only try to read this many times before failing to avoid waiting here
   // very long in case of contention with the writer.
   int contention_count = -1;
   base::subtle::Atomic32 version;
   do {
     version = seqlock->ReadBegin();
     memcpy(temp, from, size);
     ++contention_count;
     if (contention_count == kMaximumContentionCount)
       break;
   } while (seqlock->ReadRetry(version));
 
   if (contention_count >= kMaximumContentionCount) {
     // We failed to successfully read, presumably because the hardware
     // thread was taking unusually long. Don't copy the data to the output
     // buffer, and simply leave what was there before.
     return false;
   }
 
   // New data was read successfully, copy it into the output buffer.
   memcpy(final, temp, size);
   return true;
 }
 
 }  // namespace internal
 }  // namespace content