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Screen shot: https://screenshot.googleplex.com/My1OamJqnYy

The CL only includes web UI logic, the code that triggers this UI
will be included in a follow up CL.

Bug: 1013370
Change-Id: I2b785ea711a0c62c9b7fa3c3dcac811307289d1f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1856804
Commit-Queue: Xinghui Lu <xinghuilu@chromium.org>
Reviewed-by: Daniel Rubery <drubery@chromium.org>
Reviewed-by: Varun Khaneja <vakh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#705693}