Use base::Optional<int32_t> in H264POC::ComputePicOrderCnt(...)

media/gpu/vt_video_decode_accelerator_mac.h

Index: media/gpu/vt_video_decode_accelerator_mac.h
diff --git a/media/gpu/vt_video_decode_accelerator_mac.h b/media/gpu/vt_video_decode_accelerator_mac.h
index 9a69ef5525d955168e90472f0b07bad5ddcc77ac..566e51cf5a343e9a52460be5e4c2bcfe41edd286 100644
--- a/media/gpu/vt_video_decode_accelerator_mac.h
+++ b/media/gpu/vt_video_decode_accelerator_mac.h
@@ -157,12 +157,6 @@ class VTVideoDecodeAccelerator : public VideoDecodeAccelerator,
   // Methods for interacting with VideoToolbox. Run on |decoder_thread_|.
   //
 
-  // Compute the |pic_order_cnt| for a frame. Returns true or calls
-  // NotifyError() before returning false.
-  bool ComputePicOrderCnt(const H264SPS* sps,
-                          const H264SliceHeader& slice_hdr,
-                          Frame* frame);
-
   // Set up VideoToolbox using the current SPS and PPS. Returns true or calls
   // NotifyError() before returning false.
   bool ConfigureDecoder();