Cleanup PreferenceMACs on browser_tests startup

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"
 #include "base/memory/ptr_util.h"
 #include "base/numerics/safe_conversions.h"
 #include "base/strings/string_split.h"
+#include "base/strings/string_util.h"
 #include "base/strings/stringprintf.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/values.h"
 #include "base/win/registry.h"
 #include "services/preferences/public/cpp/tracked/tracked_preference_histogram_names.h"
 
 using base::win::RegistryValueIterator;
 
 namespace {
 
@@ skipping 41 matching lines @@
     return key.DeleteKey(L"") == ERROR_SUCCESS;
   }
   return false;
 }
 
 }  // namespace
 
 RegistryHashStoreContentsWin::RegistryHashStoreContentsWin(
     const base::string16& registry_path,
     const base::string16& store_key)
-    : preference_key_name_(registry_path + L"\\PreferenceMACs\\" + store_key) {}
+    : preference_key_name_(registry_path + L"\\PreferenceMACs\\" + store_key),
+      reset_on_delete_(base::StartsWith(store_key,
+                                        base::ScopedTempDir::GetTempDirPrefix(),
+                                        base::CompareCase::INSENSITIVE_ASCII)) {
+}
+
+RegistryHashStoreContentsWin::~RegistryHashStoreContentsWin() {
+  if (reset_on_delete_)
+    Reset();
+}
 
 RegistryHashStoreContentsWin::RegistryHashStoreContentsWin(
     const RegistryHashStoreContentsWin& other) = default;
 
 bool RegistryHashStoreContentsWin::IsCopyable() const {
   return true;
 }
 
 std::unique_ptr<HashStoreContents> RegistryHashStoreContentsWin::MakeCopy()
     const {
@@ skipping 88 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";
 }