Delete more event tracing macros

Also tried to clean up the comments to be clearer.

Bug: skia:
Change-Id: I9762564a7f59bbfbd6a43afe902596d25ff1d523
Reviewed-on: https://skia-review.googlesource.com/25364
Reviewed-by: Mike Klein <mtklein@chromium.org>
Commit-Queue: Brian Osman <brianosman@google.com>
3 files changed