[chrome:omnibox] Colored output for 'additional properties' column.

The additional properties column is displayed only when there is an unaccounted
property on matches returned form the page handler; ideally, it should never be
shown. When it is shown, originally (before any chrome:omnibox refresh CL's), we
displayed 1 column per unaccounted property, each in the format of
"propertyName=propertyValue". Previous CL's changed it to be a single column of
stringified JSON. This CL adds color to it.

Bug: 891303
Change-Id: I84d4655b87d3aea2a94cd2ab74051b5d8edd0007
Reviewed-on: https://chromium-review.googlesource.com/c/1368457
Reviewed-by: Tommy Li <tommycli@chromium.org>
Commit-Queue: manuk hovanesian <manukh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#614882}
2 files changed