client lib: Add a DCHECK to ThreadTracks for tid != 0 am: 311b3607cf am: 4c346e7d89
client lib: Add a DCHECK to ThreadTracks for tid != 0 am: 311b3607cf am: 4c346e7d89

Change-Id: Ib6c018e9343b4e1d9c9b32345fc7c1d59798d28c

google/perfetto,google/perfetto,google/perfetto,google/perfetto,google/perfetto,google/perfetto,google/perfetto,google/perfetto