Get rid of base::SharedMemory::NULLHandle();

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 <stddef.h>
 #include <sys/mman.h>
@@ skipping 20 matching lines @@
   Unmap();
   Close();
 }
 
 // static
 bool SharedMemory::IsHandleValid(const SharedMemoryHandle& handle) {
   return handle.IsValid();
 }
 
 // static
-SharedMemoryHandle SharedMemory::NULLHandle() {
-  return SharedMemoryHandle();
-}
-
-// static
 void SharedMemory::CloseHandle(const SharedMemoryHandle& handle) {
   DCHECK(handle.IsValid());
   handle.Close();
 }
 
 // static
 SharedMemoryHandle SharedMemory::DuplicateHandle(
     const SharedMemoryHandle& handle) {
   return handle.Duplicate();
 }
@@ skipping 87 matching lines @@
   *new_handle = shm_.Duplicate();
 
   if (close_self) {
     Unmap();
     Close();
   }
   return new_handle->IsValid();
 }
 
 }  // namespace base