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This makes a few changes to update colors to material colors as well as
adding the dark mode support, with the input of a designer.

The biggest are:
 - changing the background color of an item to google-blue-50/
   google-grey-900 (dark mode)
 - removing the background for the license section, so it's the same
   background color as the overall item
 - making the title and license text color dark blue in light mode
   instead of black (it's still light grey in dark mode)

The bug has some screenshots.

Bug: 1006216
Change-Id: I870609d48f52a617533f4191840cc4daa8be4f19
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1824089Reviewed-by: Dan Beam <dbeam@chromium.org>
Commit-Queue: Robbie Gibson <rkgibson@google.com>
Cr-Commit-Position: refs/heads/master@{#700172}