Update from https://crrev.com/311076

base/files/memory_mapped_file.cc

 // Copyright 2013 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/files/memory_mapped_file.h"
 
 #include "base/files/file_path.h"
 #include "base/logging.h"
 #include "base/sys_info.h"
 
@@ skipping 13 matching lines @@
 
 bool MemoryMappedFile::Region::operator==(
     const MemoryMappedFile::Region& other) const {
   return other.offset == offset && other.size == size;
 }
 
 MemoryMappedFile::~MemoryMappedFile() {
   CloseHandles();
 }
 
+#if !defined(OS_NACL)
 bool MemoryMappedFile::Initialize(const FilePath& file_name) {
   if (IsValid())
     return false;
 
   file_.Initialize(file_name, File::FLAG_OPEN | File::FLAG_READ);
 
   if (!file_.IsValid()) {
     DLOG(ERROR) << "Couldn't open " << file_name.AsUTF8Unsafe();
     return false;
   }
@@ skipping 34 matching lines @@
                                                     int64* aligned_start,
                                                     int64* aligned_size,
                                                     int32* offset) {
   // Sadly, on Windows, the mmap alignment is not just equal to the page size.
   const int64 mask = static_cast<int64>(SysInfo::VMAllocationGranularity()) - 1;
   DCHECK_LT(mask, std::numeric_limits<int32>::max());
   *offset = start & mask;
   *aligned_start = start & ~mask;
   *aligned_size = (size + *offset + mask) & ~mask;
 }
+#endif
 
 }  // namespace base