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- Adds SupportsAmbientColor() method to PowerManagerClient
- Corresponding platform change [1]

[1] - https://chromium-review.googlesource.com/c/chromiumos/platform2/+/1825453

BUG=b/138731765
TEST=end to end

Change-Id: I43d1532dc121b3edef099dc81bc51964b8d89f0c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1835170
Commit-Queue: Zentaro Kavanagh <zentaro@chromium.org>
Auto-Submit: Zentaro Kavanagh <zentaro@chromium.org>
Reviewed-by: Steven Bennetts <stevenjb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#704313}