Support video themes in AmbientController.

Bug: b:271180547
Change-Id: I464ccdd071fd90954a86a72b35d3a6cf68b3cc16
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4308337


Reviewed-by: Xiaohui Chen <xiaohuic@chromium.org>
Reviewed-by: Tao Wu <wutao@chromium.org>
Commit-Queue: Eric Sum <esum@google.com>
Cr-Commit-Position: refs/heads/main@{#1118922}