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 76ee57f3cd1caa8aef225a751e17b6578fac7985..cb92ae77eddff665700549ea746c4efaeca80dff 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"
@@ -68,20 +66,38 @@ 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) {
+  DCHECK(registry_path_ == L"" || registry_path_ == registry_path);
+  registry_path_ = registry_path;

[gab, 2017/06/12 15:52:16]

if (resitry_path_.empty())
  registry_path_ = registry_path;
else
  DCHECK_EQ(registry_path_, registry_path);

(avoids string copy in = case)

[proberge, 2017/06/12 18:46:02]

Done.

+}
+
+TempScopedDirRegistryCleaner::~TempScopedDirRegistryCleaner() {
+  DCHECK(registry_path_ != L"");

[gab, 2017/06/12 15:52:16]

DCHECK(!registry_path_.empty());

[proberge, 2017/06/12 18:46:02]

Done.

+  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)) {
-}
-
-RegistryHashStoreContentsWin::~RegistryHashStoreContentsWin() {
-  if (reset_on_delete_)
-    Reset();
+      temp_dir_cleaner_(temp_dir_cleaner) {

[gab, 2017/06/12 15:52:16]

std::move

[proberge, 2017/06/12 18:46:02]

Done.

+  if (temp_dir_cleaner_)
+    static_cast<TempScopedDirRegistryCleaner*>(temp_dir_cleaner_.get())
+        ->SetRegistryPath(preference_key_name_);
 }
 
 RegistryHashStoreContentsWin::RegistryHashStoreContentsWin(
@@ -101,12 +117,7 @@ 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;
-  }
+  DeleteRegistryKey(preference_key_name_);
 }
 
 bool RegistryHashStoreContentsWin::GetMac(const std::string& path,