Ensure SkTraceEvent.h is kept as the canonical header for tracing

Follow up to I43e1aad45fe3156ef64ae4d22fe6709ef5467742 to unblock
Android roll.

This Android specific dependency inversion should be fixed, but I'd like
to unblock the Android roll first.

Change-Id: I86027d51eadf704feef664ae06b7e937e895b8bb
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/980138
Commit-Queue: Ben Wagner <bungeman@google.com>
Reviewed-by: Ben Wagner <bungeman@google.com>
Auto-Submit: Noelle Scobie <nscobie@google.com>