Fix a race condition in ~RegistryHashStoreContentsWin

services/preferences/tracked/registry_hash_store_contents_win.cc

Index: services/preferences/tracked/registry_hash_store_contents_win.cc
diff --git a/services/preferences/tracked/registry_hash_store_contents_win.cc b/services/preferences/tracked/registry_hash_store_contents_win.cc
index 4b80458334dd70c59424c6eff7ae2ab05876c4cf..354a5bfac4b84e41602b6cb75a967c9a6dd125c0 100644
--- a/services/preferences/tracked/registry_hash_store_contents_win.cc
+++ b/services/preferences/tracked/registry_hash_store_contents_win.cc
@@ -6,12 +6,10 @@
 
 #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"
@@ -68,21 +66,43 @@ bool ClearSplitMac(const base::string16& reg_key_name,
   return false;
 }
 
+// Deletes |reg_key_name| if it exists.
+void DeleteRegistryKey(const base::string16& reg_key_name) {
+  base::win::RegKey key;
+  if (key.Open(HKEY_CURRENT_USER, reg_key_name.c_str(),
+               KEY_SET_VALUE | KEY_WOW64_32KEY) == ERROR_SUCCESS) {
+    LONG result = key.DeleteKey(L"");
+    DCHECK(result == ERROR_SUCCESS || result == ERROR_FILE_NOT_FOUND) << result;
+  }
+}
+
 }  // namespace
 
+void TempScopedDirRegistryCleaner::SetRegistryPath(
+    const base::string16& registry_path) {
+  if (registry_path_.empty())
+    registry_path_ = registry_path;
+  else
+    DCHECK_EQ(registry_path_, registry_path);
+}
+
+TempScopedDirRegistryCleaner::~TempScopedDirRegistryCleaner() {
+  DCHECK(!registry_path_.empty());
+  DeleteRegistryKey(registry_path_);
+}
+
 RegistryHashStoreContentsWin::RegistryHashStoreContentsWin(
     const base::string16& registry_path,
-    const base::string16& store_key)
+    const base::string16& store_key,
+    scoped_refptr<TempScopedDirCleaner> temp_dir_cleaner)
     : preference_key_name_(registry_path + L"\\PreferenceMACs\\" + store_key),
-      reset_on_delete_(base::StartsWith(store_key,
-                                        base::ScopedTempDir::GetTempDirPrefix(),
-                                        base::CompareCase::INSENSITIVE_ASCII)) {
+      temp_dir_cleaner_(std::move(temp_dir_cleaner)) {
+  if (temp_dir_cleaner_)
+    static_cast<TempScopedDirRegistryCleaner*>(temp_dir_cleaner_.get())
+        ->SetRegistryPath(preference_key_name_);
 }
 
-RegistryHashStoreContentsWin::~RegistryHashStoreContentsWin() {
-  if (reset_on_delete_)
-    Reset();
-}
+RegistryHashStoreContentsWin::~RegistryHashStoreContentsWin() = default;
 
 RegistryHashStoreContentsWin::RegistryHashStoreContentsWin(
     const RegistryHashStoreContentsWin& other) = default;
@@ -101,14 +121,7 @@ base::StringPiece RegistryHashStoreContentsWin::GetUMASuffix() const {
 }
 
 void RegistryHashStoreContentsWin::Reset() {
-  base::win::RegKey key;
-  if (key.Open(HKEY_CURRENT_USER, preference_key_name_.c_str(),
-               KEY_SET_VALUE | KEY_WOW64_32KEY) == ERROR_SUCCESS) {
-    LONG result = key.DeleteKey(L"");
-    DCHECK(result == ERROR_SUCCESS || result == ERROR_FILE_NOT_FOUND ||
-           result == ERROR_ACCESS_DENIED || result == ERROR_KEY_DELETED)
-        << result;
-  }
+  DeleteRegistryKey(preference_key_name_);
 }
 
 bool RegistryHashStoreContentsWin::GetMac(const std::string& path,