Block files >20MB in presubmit check

To avoid bloating the chromium/src git repo with large binary
files, this adds a check that files are not too large and suggests
to use cloud storage otherwise.

Now without trying to check the size of deleted files and with the
limit increased to 20MB.

R=dpranke@chromium.org

Bug: 956017
Change-Id: Ieeb2e1a37017a375f9da7a48c7713077c4929ff3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1581971
Commit-Queue: Daniel Bratell <bratell@opera.com>
Auto-Submit: Daniel Bratell <bratell@opera.com>
Reviewed-by: Dirk Pranke <dpranke@chromium.org>
Cr-Commit-Position: refs/heads/master@{#655002}
1 file changed