Implement Add/Remove FileDescriptorWatch for the PerfettoTaskRunner

This is needed in a future CL to connect via the IPC mechanism used by
the system Perfetto service on Android.

Bug: 966047
Change-Id: I0521d9e91cc6d3332607be747743a2ab590255ed
Commit-Queue: Stephen Nusko <>
Auto-Submit: Stephen Nusko <>
Reviewed-by: Eric Seckler <>
Reviewed-by: Sami Kyöstilä <>
Reviewed-by: François Doray <>
Cr-Commit-Position: refs/heads/master@{#672063}
5 files changed