tracing: Add missing 'explicit' to LegacyTraceId constructor
tracing: Add missing 'explicit' to LegacyTraceId constructor

Change-Id: I4b34ea70c014e3d6d61b950afe0330274459c71d
google/perfetto,google/perfetto,google/perfetto,google/perfetto,google/perfetto,google/perfetto,google/perfetto,google/perfetto