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While here, also fix a bug in which the rectangle in which the filter is
assumed to be visible was also mapped through the filter, and update unit
tests accordingly.

BUG=600821
CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_rel

Review-Url: https://codereview.chromium.org/2015343002
Cr-Commit-Position: refs/heads/master@{#397192}