This code is highly repetitive, and while we've held off on large
refactorings (using "Builder" classes, templates or macros), it's
useful to find a few common points that don't change very much.

Bug: 
Change-Id: Ib0880558cf667f5d07c8343328461609ccb1e6b1
Reviewed-on: https://chromium-review.googlesource.com/848913Reviewed-by: Daniel Clifford <danno@chromium.org>
Commit-Queue: Michael Stanton <mvstanton@chromium.org>
Cr-Commit-Position: refs/heads/master@{#50338}