Fix signed integers in track_run_iterator.cc

media/formats/mp4/track_run_iterator.cc

Index: media/formats/mp4/track_run_iterator.cc
diff --git a/media/formats/mp4/track_run_iterator.cc b/media/formats/mp4/track_run_iterator.cc
index f109873b27a19251a5b9d2f4424fb26e31e7f912..d3543f40aa55d2f780777d7f8ead8cde7d700eea 100644
--- a/media/formats/mp4/track_run_iterator.cc
+++ b/media/formats/mp4/track_run_iterator.cc
@@ -18,8 +18,8 @@ namespace media {
 namespace mp4 {
 
 struct SampleInfo {
-  int size;
-  int duration;
+  uint32_t size;
+  uint32_t duration;
   int cts_offset;
   bool is_keyframe;
   uint32_t cenc_group_description_index;