Update from https://crrev.com/333737

base/memory/shared_memory_nacl.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 "base/memory/shared_memory.h"
 
 #include <errno.h>
 #include <fcntl.h>
 #include <sys/mman.h>
 #include <sys/stat.h>
 #include <unistd.h>
 
 #include <limits>
 
 #include "base/logging.h"
 
 namespace base {
 
 SharedMemory::SharedMemory()
     : mapped_file_(-1),
-      inode_(0),
       mapped_size_(0),
       memory_(NULL),
       read_only_(false),
       requested_size_(0) {
 }
 
 SharedMemory::SharedMemory(SharedMemoryHandle handle, bool read_only)
     : mapped_file_(handle.fd),
-      inode_(0),
       mapped_size_(0),
       memory_(NULL),
       read_only_(read_only),
       requested_size_(0) {
 }
 
 SharedMemory::SharedMemory(SharedMemoryHandle handle, bool read_only,
                            ProcessHandle process)
     : mapped_file_(handle.fd),
-      inode_(0),
       mapped_size_(0),
       memory_(NULL),
       read_only_(read_only),
       requested_size_(0) {
   NOTREACHED();
 }
 
 SharedMemory::~SharedMemory() {
   Unmap();
   Close();
 }
 
 // static
 bool SharedMemory::IsHandleValid(const SharedMemoryHandle& handle) {
   return handle.fd >= 0;
 }
 
 // static
 SharedMemoryHandle SharedMemory::NULLHandle() {
   return SharedMemoryHandle();
 }
 
 // static
 void SharedMemory::CloseHandle(const SharedMemoryHandle& handle) {
   DCHECK_GE(handle.fd, 0);
   if (close(handle.fd) < 0)
     DPLOG(ERROR) << "close";
 }
 
+// static
+SharedMemoryHandle SharedMemory::DuplicateHandle(
+    const SharedMemoryHandle& handle) {
+  int duped_handle = HANDLE_EINTR(dup(handle.fd));
+  if (duped_handle < 0)
+    return base::SharedMemory::NULLHandle();
+  return base::FileDescriptor(duped_handle, true);
+}
+
 bool SharedMemory::CreateAndMapAnonymous(size_t size) {
   // Untrusted code can't create descriptors or handles.
   return false;
 }
 
 bool SharedMemory::Create(const SharedMemoryCreateOptions& options) {
   // Untrusted code can't create descriptors or handles.
   return false;
 }
 
@@ skipping 80 matching lines @@
   new_handle->auto_close = true;
 
   if (close_self) {
     Unmap();
     Close();
   }
   return true;
 }
 
 }  // namespace base