Add tracing for QuotaManager deletion jobs

To better understand and debug issues with browsing data deletions,
add tracing for all asynchronous deletion tasks.

Bug: 932083
Change-Id: I96ecc8e79cbf35bd4d18ecc1a068f0456dc01880
Reviewed-on: https://chromium-review.googlesource.com/c/1472622
Reviewed-by: Joshua Bell <jsbell@chromium.org>
Commit-Queue: Christian Dullweber <dullweber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#632560}
1 file changed