GitLab

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

Bug: 1018739
Change-Id: I966303321f4d8f90504d11d9f42b0eab3cfce0bd
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2440846Reviewed-by: Kenneth Russell <kbr@chromium.org>
Commit-Queue: Sylvain Defresne <sdefresne@chromium.org>
Cr-Commit-Position: refs/heads/master@{#813146}