GitLab

In order to make settings sliders more functional for users of screen
readers we are adding more descriptive ARIA labels.

-Update aria-roledescription to describe to users the context of the
 min and max values of a slider.

For reference:
 Current slider ARIA output: "Slider. 120 percent. Min 60, Max 820"
 Video: https://bugs.chromium.org/p/chromium/issues/detail?id=1015839#c5

 Expected slider ARIA output: "Slider: Slowest to Fastest. 120 percent. Min 60 Max 820"
 Video: https://bugs.chromium.org/p/chromium/issues/detail?id=1015839#c9

Bug: 1015839
Change-Id: Iff2ea48b9badde05c93534ed1f2d283abef87bc9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1906941
Commit-Queue: Gavin Williams <gavinwill@chromium.org>
Reviewed-by: Hector Carmona <hcarmona@chromium.org>
Reviewed-by: Bailey Berro <baileyberro@chromium.org>
Cr-Commit-Position: refs/heads/master@{#717201}