chore: Use thread_local: base/threading/ (#37600)

https://chromium-review.googlesource.com/c/chromium/src/+/4335524

shell/browser/browser_linux.cc

@@ -28,8 +28,8 @@ const char kXdgSettingsDefaultSchemeHandler[] = "default-url-scheme-handler";
 
 // The use of the ForTesting flavors is a hack workaround to avoid having to
 // patch these as friends into the associated guard classes.
-class LaunchXdgUtilityScopedAllowBaseSyncPrimitives
-    : public base::ScopedAllowBaseSyncPrimitivesForTesting {};
+class [[maybe_unused, nodiscard]] LaunchXdgUtilityScopedAllowBaseSyncPrimitives
+    : public base::ScopedAllowBaseSyncPrimitivesForTesting{};
 
 bool LaunchXdgUtility(const std::vector<std::string>& argv, int* exit_code) {
   *exit_code = EXIT_FAILURE;