Do not rely on identical string constants having distinct pointers.

chrome/tools/disable_outdated_build_detector/google_update_integration.h

 // Copyright 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.
 
 #ifndef CHROME_TOOLS_DISABLE_OUTDATED_BUILD_DETECTOR_GOOGLE_UPDATE_INTEGRATION_H_
 #define CHROME_TOOLS_DISABLE_OUTDATED_BUILD_DETECTOR_GOOGLE_UPDATE_INTEGRATION_H_
 
 #include "base/strings/string16.h"
 #include "chrome/tools/disable_outdated_build_detector/constants.h"
 
 namespace base {
 namespace win {
 class RegKey;
 }
 }
 
 // A structure containing the values that comprise the Google Update installer
 // result API.
 struct ResultInfo {
   InstallerResult installer_result;
   ExitCode installer_error;
   uint32_t installer_extra_code1;
 };
 
+// An identifier of an app's registration with Google Update.
+enum class App {
+  CHROME_BROWSER,
+  CHROME_BINARIES,
+};
+
 // Opens the Google Update ClientState key in the registry for the app
-// identified by |app_guid| at |system_level|. Returns ERROR_SUCCESS or another
+// identified by |app| at |system_level|. Returns ERROR_SUCCESS or another
 // Windows error value.
-uint32_t OpenClientStateKey(bool system_level,
-                            const wchar_t* app_guid,
-                            base::win::RegKey* key);
+uint32_t OpenClientStateKey(bool system_level, App app, base::win::RegKey* key);
 
 // Writes the data in |result_info| into Chrome's ClientState key.
 void WriteResultInfo(bool system_level, const ResultInfo& result_info);
 
 // Returns |true| if |brand| represents an organic brand code.
 bool IsOrganic(const base::string16& brand);
 
 #endif  // CHROME_TOOLS_DISABLE_OUTDATED_BUILD_DETECTOR_GOOGLE_UPDATE_INTEGRATION_H_