profiling: Fix pprof mapping ids.
profiling: Fix pprof mapping ids.

The pprof converter assumes mapping ids != 0.

Change-Id: Ib6ebd2a9d06438617ba52af81e413b49b99291ea

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