Move deep scanning utils to new file instead of CheckClientDownloadReq

Change-Id: Ic4ef01d8a4e07a41253e36b2ea5e9086db81765f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1937648
Commit-Queue: Dominique Fauteux-Chapleau <domfc@chromium.org>
Reviewed-by: Daniel Rubery <drubery@chromium.org>
Cr-Commit-Position: refs/heads/master@{#719581}
8 files changed