Now that Chromium is switched to ANGLE's new Platform tracing
methods, we can junk the old APIs.

BUG=angleproject:966
BUG=436191

Change-Id: Ie2564eed9e5ce4604e0dcd4582618e7467b2d590
Reviewed-on: https://chromium-review.googlesource.com/264934Tested-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Kenneth Russell <kbr@chromium.org>
Reviewed-by: Brandon Jones <bajones@chromium.org>