MSE: Update DTS by the same delta as PTS during partial append window trimming

media/filters/frame_processor.cc

Index: media/filters/frame_processor.cc
diff --git a/media/filters/frame_processor.cc b/media/filters/frame_processor.cc
index 0528ff7c806f25436991c875ce87abcb87b6289c..6c71ea507240c58543e369184f9fd5d721be8d93 100644
--- a/media/filters/frame_processor.cc
+++ b/media/filters/frame_processor.cc
@@ -388,10 +388,11 @@ bool FrameProcessor::HandlePartialAppendWindowTrimming(
         append_window_start - buffer->timestamp(), base::TimeDelta()));
 
     // Adjust the timestamp of this buffer forward to |append_window_start| and
-    // decrease the duration to compensate.
+    // decrease the duration to compensate. Adjust DTS by the same delta as PTS
+    // to help prevent spurious discontinuities when DTS > PTS.
+    base::TimeDelta pts_delta = append_window_start - buffer->timestamp();
     buffer->set_timestamp(append_window_start);
-    buffer->SetDecodeTimestamp(
-        DecodeTimestamp::FromPresentationTime(append_window_start));
+    buffer->SetDecodeTimestamp(buffer->GetDecodeTimestamp() + pts_delta);
     buffer->set_duration(frame_end_timestamp - append_window_start);
     processed_buffer = true;
   }