--- a/dom/media/Benchmark.cpp
+++ b/dom/media/Benchmark.cpp
@@ -55,18 +55,17 @@ VP9Benchmark::IsVP9DecodeFast()
                     {
                       Preferences::GetInt("media.benchmark.frames", 300), // frames to measure
                       1, // start benchmarking after decoding this frame.
                       8, // loop after decoding that many frames.
                       TimeDuration::FromMilliseconds(
                         Preferences::GetUint("media.benchmark.timeout", 1000))
                     });
     estimiser->Run()->Then(
-      // Non-DocGroup version of AbstractThread::MainThread for utility function.
-      AbstractThread::MainThread(), __func__,
+      SystemGroup::AbstractMainThreadFor(TaskCategory::Other), __func__,
       [](uint32_t aDecodeFps) {
         if (XRE_IsContentProcess()) {
           dom::ContentChild* contentChild = dom::ContentChild::GetSingleton();
           if (contentChild) {
             contentChild->SendNotifyBenchmarkResult(NS_LITERAL_STRING("VP9"),
                                                     aDecodeFps);
           }
         } else {