AudioConverter: Express delay in frames rather than msec.

media/cast/test/fake_media_source.h

Index: media/cast/test/fake_media_source.h
diff --git a/media/cast/test/fake_media_source.h b/media/cast/test/fake_media_source.h
index d3dc90df4138cc0f824dc1b920ca39272a5c92a1..8fb9fab518f1d9b674e01b143bb087bf7f2ba118 100644
--- a/media/cast/test/fake_media_source.h
+++ b/media/cast/test/fake_media_source.h
@@ -108,8 +108,8 @@ class FakeMediaSource : public media::AudioConverter::InputCallback {
   void Decode(bool decode_audio);
 
   // media::AudioConverter::InputCallback implementation.
-  double ProvideInput(media::AudioBus* output_bus, base::TimeDelta buffer_delay)
-      final;
+  double ProvideInput(media::AudioBus* output_bus,
+                      uint32_t frames_delayed) final;
 
   AVStream* av_audio_stream();
   AVStream* av_video_stream();