TrackEvent: Add parent uuid field and move track descriptor extension points

This patch adds the parent_uuid field to the track descriptor so that
tracks can be grouped in a hierarchy and moves the extension points
(e.g., Chrome-specific track descriptor fields) to their own top-level
messages to make it easier to add custom descriptor extensions in the
future.

Bug: 132678367
Change-Id: I448df34a7acff5809cd768b25f3d22d2ac27cf73
diff --git a/BUILD b/BUILD
index 85d887b..0242d73 100644
--- a/BUILD
+++ b/BUILD
@@ -2347,6 +2347,8 @@
         "protos/perfetto/trace/track_event/chrome_histogram_sample.proto",
         "protos/perfetto/trace/track_event/chrome_keyed_service.proto",
         "protos/perfetto/trace/track_event/chrome_legacy_ipc.proto",
+        "protos/perfetto/trace/track_event/chrome_process_descriptor.proto",
+        "protos/perfetto/trace/track_event/chrome_thread_descriptor.proto",
         "protos/perfetto/trace/track_event/chrome_user_event.proto",
         "protos/perfetto/trace/track_event/debug_annotation.proto",
         "protos/perfetto/trace/track_event/log_message.proto",