Rename GraphicsContext high contrast unit tests to dark mode.

Bug: 938511
Change-Id: I5fe57c9529bc59340329365fa68255a5c46b440a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1582433
Auto-Submit: Aran Gilman <gilmanmh@google.com>
Reviewed-by: Stephen Chenney <schenney@chromium.org>
Commit-Queue: Aran Gilman <gilmanmh@google.com>
Cr-Commit-Position: refs/heads/master@{#654034}
1 file changed