Bug 1546324 - use TimeUnit version modular. r=bryce

The value of `mAudioDecodedDuration` can be larger than `int32`, so we should use the modular function which accepts `TimeUnit`as a input.

Differential Revision: https://phabricator.services.mozilla.com/D28536

--HG--
extra : moz-landing-system : lando

dom/media/MediaDecoderStateMachine.cpp

@@ -3933,7 +3933,7 @@ void MediaDecoderStateMachine::AdjustByLooping(media::TimeUnit& aTime) const {
   MOZ_ASSERT(OnTaskQueue());
   if (mAudioDecodedDuration.isSome() &&
       mAudioDecodedDuration.ref().IsPositive()) {
-    aTime = aTime % mAudioDecodedDuration.ref().ToMicroseconds();
+    aTime = aTime % mAudioDecodedDuration.ref();
   }
 }