trace writer: Fix chunk_id field size
trace writer: Fix chunk_id field size

ChunkIDs are 32bit, but TraceWriter was wrapping at 16bit :O

Change-Id: I6d43cb4b9cd2d60a91fff6169c98a8004b87866a
google/perfetto,google/perfetto,google/perfetto,google/perfetto,google/perfetto,google/perfetto,google/perfetto,google/perfetto