Removed more BrowserThread::FILE usage from tracing

R=gab@chromium.org
BUG=667892

Change-Id: I7c0d7b19f97922a27966f3dcae5fff662f018e67
Reviewed-on: https://chromium-review.googlesource.com/674060
Commit-Queue: oysteine <oysteine@chromium.org>
Reviewed-by: oysteine <oysteine@chromium.org>
Reviewed-by: Gabriel Charette <gab@chromium.org>
Cr-Commit-Position: refs/heads/master@{#503973}
5 files changed