file_contexts

Perfetto is a performance instrumentation and logging framework,
living in AOSP's /external/pefetto.
Perfetto introduces in the system one binary and two daemons
(the binary can specialize in either depending on the cmdline).

1) traced: unprivileged daemon. This is architecturally similar to logd.
   It exposes two UNIX sockets:
   - /dev/socket/traced_producer : world-accessible, allows to stream
     tracing data. A tmpfs file descriptor is sent via SCM_RIGHTS
     from traced to each client process, which needs to be able to
     mmap it R/W (but not X)
   - /dev/socket/traced_consumer : privilege-accessible (only from:
     shell, statsd). It allows to configure tracing and read the trace
     buffer.
2) traced_probes: privileged daemon. This needs to:
   - access tracingfs (/d/tracing) to turn tracing on and off.
   - exec atrace
   - connect to traced_producer to stream data to traced.

init.rc file:
https://android-review.googlesource.com/c/platform/external/perfetto/+/575382/14/perfetto.rc

Bug: 70942310
Change-Id: Ia3b5fdacbd5a8e6e23b82f1d6fabfa07e4abc405