[mojo-edk] Switch shared buffers to use Mach on OSX.

mojo/edk/embedder/platform_shared_buffer.cc

 // Copyright 2014 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 "mojo/edk/embedder/platform_shared_buffer.h"
 
 #include <stddef.h>
 
 #include <utility>
 
@@ skipping 157 matching lines @@
     : num_bytes_(num_bytes) {}
 
 PlatformSharedBuffer::~PlatformSharedBuffer() {}
 
 bool PlatformSharedBuffer::Init() {
   DCHECK(!shared_memory_);
 
   base::SharedMemoryCreateOptions options;
   options.size = num_bytes_;
 #if defined(OS_MACOSX) && !defined(OS_IOS)
-  // TODO(crbug.com/582468): Support Mach shared memory.
-  options.type = base::SharedMemoryHandle::POSIX;
+  options.type = base::SharedMemoryHandle::MACH;
 #endif
 
   shared_memory_.reset(new base::SharedMemory);
   return shared_memory_->Create(options);
 }
 
 bool PlatformSharedBuffer::InitFromPlatformHandle(
     ScopedPlatformHandle platform_handle) {
   DCHECK(!shared_memory_);
 
@@ skipping 50 matching lines @@
   base_ = static_cast<char*>(shared_memory_.memory()) + offset_rounding;
   return true;
 }
 
 void PlatformSharedBufferMapping::Unmap() {
   shared_memory_.Unmap();
 }
 
 }  // namespace edk
 }  // namespace mojo