Provide flag to set a deterministic GC schedule. The GC still uses
multiple tasks but on a fixed growing strategy.

Change-Id: I937cf77ae0b0d1e513d4976a23c7f23a151d77c5
Reviewed-on: https://chromium-review.googlesource.com/c/1270838
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#56498}