GitLab

Remove deprecated_default_sources_assignment_filter and replace
it with explicit is_win, is_mac, etc. sections.

Bug: 1018739
Change-Id: Icfb9b5aa57f7a5232fbf41534f25c4ea1d54034c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2445473Reviewed-by: Nasko Oskov <nasko@chromium.org>
Commit-Queue: Sylvain Defresne <sdefresne@chromium.org>
Cr-Commit-Position: refs/heads/master@{#814162}