Add POSIX shared memory support for Mac

mojo/edk/embedder/platform_shared_buffer_unittest.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 <limits>
 #include <memory>
@@ skipping 178 matching lines @@
   EXPECT_EQ('x', static_cast<char*>(mapping2->GetBase())[0]);
 
   static_cast<char*>(mapping2->GetBase())[1] = 'y';
   EXPECT_EQ('y', static_cast<char*>(mapping1->GetBase())[51]);
 }
 
 TEST(PlatformSharedBufferTest, FromSharedMemoryHandle) {
   const size_t kBufferSize = 1234;
   base::SharedMemoryCreateOptions options;
   options.size = kBufferSize;
+#if defined(OS_MACOSX) && !defined(OS_IOS)
+  options.type = base::SharedMemoryHandle::POSIX;
+#endif
   base::SharedMemory shared_memory;
   ASSERT_TRUE(shared_memory.Create(options));
   ASSERT_TRUE(shared_memory.Map(kBufferSize));
 
   base::SharedMemoryHandle shm_handle =
       base::SharedMemory::DuplicateHandle(shared_memory.handle());
   scoped_refptr<PlatformSharedBuffer> simple_buffer(
       PlatformSharedBuffer::CreateFromSharedMemoryHandle(
           kBufferSize, false /* read_only */, shm_handle));
   ASSERT_TRUE(simple_buffer);
 
   std::unique_ptr<PlatformSharedBufferMapping> mapping =
       simple_buffer->Map(0, kBufferSize);
   ASSERT_TRUE(mapping);
 
   const int kOffset = 123;
   char* base_memory = static_cast<char*>(shared_memory.memory());
   char* mojo_memory = static_cast<char*>(mapping->GetBase());
   base_memory[kOffset] = 0;
   EXPECT_EQ(0, mojo_memory[kOffset]);
   base_memory[kOffset] = 'a';
   EXPECT_EQ('a', mojo_memory[kOffset]);
   mojo_memory[kOffset] = 'z';
   EXPECT_EQ('z', base_memory[kOffset]);
 }
 
 }  // namespace
 }  // namespace edk
 }  // namespace mojo