Add more values to DownloadMimeTypeResult UMA enum.

.exe and .apk could be dangerous downloads and it would be useful to
know if Chrome should use Safe Browsing for blacklisting these
downloads.

.zip is probably the most common downloaded format, so logging it can
make "other" bucket smaller.

Bug: None
Cq-Include-Trybots: luci.chromium.try:ios-simulator-cronet;luci.chromium.try:ios-simulator-full-configs
Change-Id: Icbd76954c57756169ef942cfddfce29d8a34861c
Reviewed-on: https://chromium-review.googlesource.com/1227132
Commit-Queue: Eugene But <eugenebut@chromium.org>
Reviewed-by: Mark Pearson <mpearson@chromium.org>
Reviewed-by: Sylvain Defresne <sdefresne@chromium.org>
Cr-Commit-Position: refs/heads/master@{#592086}
4 files changed