Update language preference drag background for dark mode

Bug: 955632
Change-Id: I71d0327f71eac157cf2ca14e0ff51a3181d88fe6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1583105
Commit-Queue: Sinan Sahin <sinansahin@google.com>
Reviewed-by: Becky Zhou <huayinz@chromium.org>
Reviewed-by: Theresa <twellington@chromium.org>
Cr-Commit-Position: refs/heads/master@{#654292}
3 files changed