Fix a race condition in ~RegistryHashStoreContentsWin

services/preferences/tracked/registry_hash_store_contents_win.cc

 // Copyright (c) 2016 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 "services/preferences/tracked/registry_hash_store_contents_win.h"
 
 #include <windows.h>
 
 #include "base/files/scoped_temp_dir.h"
 #include "base/logging.h"
@@ skipping 56 matching lines @@
   }
   return false;
 }
 
 }  // namespace
 
 RegistryHashStoreContentsWin::RegistryHashStoreContentsWin(
     const base::string16& registry_path,
     const base::string16& store_key)
     : preference_key_name_(registry_path + L"\\PreferenceMACs\\" + store_key),
-      reset_on_delete_(base::StartsWith(store_key,
+      reset_on_delete_(false),
+      is_for_test_scoped_dir_(base::StartsWith(store_key,
                                         base::ScopedTempDir::GetTempDirPrefix(),
                                         base::CompareCase::INSENSITIVE_ASCII)) {
 }
 
 RegistryHashStoreContentsWin::~RegistryHashStoreContentsWin() {
   if (reset_on_delete_)
     Reset();
 }
 
+// To properly write to the Windows registry when Chrome is shutting down,
+// a clone of this object is created and passed to a callback which will be
+// run on a different thread. This could create a race condition if both the
+// orignal and clone are destructed (and try to delete the registry key) at

[gab, 2017/06/05 18:04:21]

s/destructed/destroyed/

[proberge, 2017/06/06 21:29:52]

Done.

+// the same time: only the clone should attempt to delete the registry key.
+// Note that this only applies for scoped temporary profiles used in tests.
 RegistryHashStoreContentsWin::RegistryHashStoreContentsWin(
-    const RegistryHashStoreContentsWin& other) = default;
+    const RegistryHashStoreContentsWin& other) :
+      preference_key_name_(other.preference_key_name_),
+      reset_on_delete_(other.is_for_test_scoped_dir_),
+      is_for_test_scoped_dir_(other.is_for_test_scoped_dir_) {
+  DCHECK_EQ(other.reset_on_delete_, false);

[gab, 2017/06/05 18:04:21]

DCHECK(!other.reset_on_delete_);

[proberge, 2017/06/06 21:29:52]

Done.

+};
 
 bool RegistryHashStoreContentsWin::IsCopyable() const {
   return true;
 }
 
 std::unique_ptr<HashStoreContents> RegistryHashStoreContentsWin::MakeCopy()
     const {
   return base::WrapUnique(new RegistryHashStoreContentsWin(*this));
 }
 
@@ skipping 85 matching lines @@
 std::string RegistryHashStoreContentsWin::GetSuperMac() const {
   NOTREACHED()
       << "RegistryHashStoreContents does not support the GetSuperMac operation";
   return NULL;
 }
 
 void RegistryHashStoreContentsWin::SetSuperMac(const std::string& super_mac) {
   NOTREACHED()
       << "RegistryHashStoreContents does not support the SetSuperMac operation";
 }