trace_processor: fix null vs 0 bug in thread table am: 1aa852a0ca am: b0a6e82b0e am: dbf79fc830
trace_processor: fix null vs 0 bug in thread table am: 1aa852a0ca am: b0a6e82b0e
am: dbf79fc830

Change-Id: Id32b63a0917dd44410956830616bc6bb4c6fd801

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