Add tracing to CanvasResource related code

BUG=788439

Cq-Include-Trybots: master.tryserver.blink:linux_trusty_blink_rel;master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2
Change-Id: Ic8d5eabeb05d0dd19d9a8e4a1f6acf0e93d9c051
Reviewed-on: https://chromium-review.googlesource.com/1094043
Reviewed-by: Fernando Serboncini <fserb@chromium.org>
Commit-Queue: Justin Novosad <junov@chromium.org>
Cr-Commit-Position: refs/heads/master@{#566219}
4 files changed