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This change fixes changes some platform checks to TOOLKIT_VIEWS and
allows the test to assume that Mac is always running with views
enabled.

Also the information about undo selection restoration has been moved
to http://crbug.com/836490.

BUG=834754,836490

Change-Id: I906e78fb4649c646f79c2d18e6d4222b7a25050d
Reviewed-on: https://chromium-review.googlesource.com/1026881Reviewed-by: Elly Fong-Jones <ellyjones@chromium.org>
Commit-Queue: Robert Liao <robliao@chromium.org>
Cr-Commit-Position: refs/heads/master@{#553623}