VTVDA: Optimize pic_order_cnt_type == 2.

media/video/h264_poc.h

Index: media/video/h264_poc.h
diff --git a/media/video/h264_poc.h b/media/video/h264_poc.h
index a2319cacd005b2cc6f775a1124973304a2161f31..90d0eb904cf54b71cc85999cce42867b5501cee4 100644
--- a/media/video/h264_poc.h
+++ b/media/video/h264_poc.h
@@ -21,11 +21,21 @@ class MEDIA_EXPORT H264POC {
 
   // Compute the picture order count for a slice, storing the result into
   // |*pic_order_cnt|.
+  // TODO(sandersd): Switch to a base::Optional<int32_t> return type.
   bool ComputePicOrderCnt(
       const H264SPS* sps,
       const H264SliceHeader& slice_hdr,
       int32_t* pic_order_cnt);
 
+  // As specified, the POC of a frame with MMCO5 changes (to zero) after
+  // decoding. We instead return 0 immediately, and flag that this has occurred
+  // by returning true here until ComputePicOrderCnt() is called again.
+  //
+  // Frames with MMCO5 do not reorder relative to frames earlier in decode
+  // order, but may reorder relative to frames later in decode order (just like
+  // IDRs).
+  bool IsPendingMMCO5() { return pending_mmco5_; }
+
   // Reset computation state. It's best (although not strictly required) to call
   // this after a seek.
   void Reset();
@@ -35,6 +45,7 @@ class MEDIA_EXPORT H264POC {
   int32_t ref_pic_order_cnt_lsb_;
   int32_t prev_frame_num_;
   int32_t prev_frame_num_offset_;
+  bool pending_mmco5_;
 
   DISALLOW_COPY_AND_ASSIGN(H264POC);
 };