Migrate //courgette to RepeatingCallback

This updates //courgette to use base::RepeatingCallback instead of
legacy base::Callback. No intended functional change is included.

This reduces the number of 'base::Bind' in //courgette from 3 to 0 as
tracked at http://goo.gl/LUVhDj

Bug: 714018
Change-Id: I40ec7c5cd7486f6b1110f13e35fd0368a4db9f3c
Reviewed-on: https://chromium-review.googlesource.com/954886
Reviewed-by: Samuel Huang <huangs@chromium.org>
Commit-Queue: Taiju Tsuiki <tzik@chromium.org>
Cr-Commit-Position: refs/heads/master@{#541735}
4 files changed