GitLab

Move the common dropdown code for sorting and choosing the default
option to SelectBehavior.

Add getSelectedOption(), sortOptions(), and isDefaultOption() to each
settings dropdown. These functions are called from SelectBehavior.

Bug: 1168346
Change-Id: I186a6e2ef18b335fdba0f81e4002f4859d27d0eb
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2638499
Commit-Queue: Gavin Williams <gavinwill@chromium.org>
Reviewed-by: Jesse Schettler <jschettler@chromium.org>
Cr-Commit-Position: refs/heads/master@{#845545}