Update from https://crrev.com/308331

base/memory/shared_memory_win.cc

 // Copyright (c) 2011 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 <aclapi.h>
 
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
@@ skipping 53 matching lines @@
       mapped_size_(0),
       lock_(NULL) {
   ::DuplicateHandle(process, handle,
                     GetCurrentProcess(), &mapped_file_,
                     read_only_ ? FILE_MAP_READ : FILE_MAP_READ |
                         FILE_MAP_WRITE,
                     FALSE, 0);
 }
 
 SharedMemory::~SharedMemory() {
+  Unmap();
   Close();
   if (lock_ != NULL)
     CloseHandle(lock_);
 }
 
 // static
 bool SharedMemory::IsHandleValid(const SharedMemoryHandle& handle) {
   return handle != NULL;
 }
 
@@ skipping 158 matching lines @@
 
   if (!DuplicateHandle(GetCurrentProcess(), mapped_file, process,
       &result, access, FALSE, options))
     return false;
   *new_handle = result;
   return true;
 }
 
 
 void SharedMemory::Close() {
-  if (memory_ != NULL) {
-    UnmapViewOfFile(memory_);
-    memory_ = NULL;
-  }
-
   if (mapped_file_ != NULL) {
     CloseHandle(mapped_file_);
     mapped_file_ = NULL;
   }
 }
 
 void SharedMemory::LockDeprecated() {
   if (lock_ == NULL) {
     std::wstring name = name_;
     name.append(L"lock");
@@ skipping 11 matching lines @@
 void SharedMemory::UnlockDeprecated() {
   DCHECK(lock_ != NULL);
   ReleaseMutex(lock_);
 }
 
 SharedMemoryHandle SharedMemory::handle() const {
   return mapped_file_;
 }
 
 }  // namespace base