Revert of base: Make shared memory backed by Mach primitives by default.

content/browser/loader/resource_buffer.cc

 // 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.
 
 #include "content/browser/loader/resource_buffer.h"
 
 #include <math.h>
 
 #include "base/logging.h"
 
@@ skipping 36 matching lines @@
   CHECK(!IsInitialized());
 
   // It would be wasteful if these are not multiples of min_allocation_size.
   CHECK_EQ(0, buffer_size % min_allocation_size);
   CHECK_EQ(0, max_allocation_size % min_allocation_size);
 
   buf_size_ = buffer_size;
   min_alloc_size_ = min_allocation_size;
   max_alloc_size_ = max_allocation_size;
 
+#if defined(OS_MACOSX) && !defined(OS_IOS)
+  return shared_mem_.CreateAndMapAnonymousMach(buf_size_);
+#else
   return shared_mem_.CreateAndMapAnonymous(buf_size_);
+#endif  // defined(OS_MACOSX) && !defined(OS_IOS)
 }
 
 bool ResourceBuffer::IsInitialized() const {
   return shared_mem_.memory() != NULL;
 }
 
 bool ResourceBuffer::ShareToProcess(
     base::ProcessHandle process_handle,
     base::SharedMemoryHandle* shared_memory_handle,
     int* shared_memory_size) {
@@ skipping 104 matching lines @@
     CHECK(alloc_sizes_.empty());
     alloc_start_ = -1;
     alloc_end_ = -1;
   } else if (alloc_start_ == buf_size_) {
     CHECK(!alloc_sizes_.empty());
     alloc_start_ = 0;
   }
 }
 
 }  // namespace content