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Scrollbar animation is required if scrollbar parameters are changed.
If any of the scrollbar parameters are changed that should trigger the
scrollbar animation. If any of the scrollbar parameter is not changed,
that doesn't require scrollbar animation. Current Patch ensures that
scrollbar is animated only when any of the scrollbar parameter is
changed.

BUG=414238

Review URL: https://codereview.chromium.org/571873003

Cr-Commit-Position: refs/heads/master@{#295978}