Revert of Refactor ScrollableArea::setScrollPosition.

Revert of Refactor ScrollableArea::setScrollPosition. (patchset #6 id:100001 of https://codereview.chromium.org/2383113003/ )

Reason for revert:
Blocks revert of another patch: https://codereview.chromium.org/2395683002/

Original issue's description:
> Refactor ScrollableArea::setScrollPosition.
>
> - Eliminate some redundant PaintLayerScrollableArea methods and
> indirection.
>
> - ScrollableArea::setScrollPosition now always clamps its argument.
> Code inspection revealed that nearly all callers were clamping
> the position argument anyway.
>
> - ScrollableArea::setScrollPosition returns immediately if the scroll
> position did not change.  This avoids a bunch of unnecessary
> work.
>
> - For the rare instances where the scroll position should not be
> clamped, or the scroll position update code should run even if the
> scroll position didn't change, add the method
> setScrollPositionUnconditionally.
>
> - When modifying the scroll position due to a change in effective
> zoom, preserve the offset from beginning of flow, rather than the
> distance from top-left of overflow area.
>
> BUG=417782
> R=skobes@chromium.org,bokan@chromium.org
> CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2
>
> Committed: https://crrev.com/cddc823c56d453758003a831fd5a2475e94c0387
> Cr-Commit-Position: refs/heads/master@{#423033}

TBR=bokan@chromium.org,skobes@chromium.org,pdr@chromium.org,szager@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=417782
Committed: https://crrev.com/6df05cf7d1cf36aa01a45db245093eab3c8bca0e
Cr-Commit-Position: refs/heads/master@{#423041}

[imcheng, 2016-10-05 01:27:48]

The CQ bit was checked by imcheng@chromium.org

[imcheng, 2016-10-05 01:27:48]

Created Revert of Refactor ScrollableArea::setScrollPosition.

[commit-bot: I haz the power, 2016-10-05 01:28:20]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-10-05 01:29:59]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-10-05 01:33:47]

Description was changed from

==========
Revert of Refactor ScrollableArea::setScrollPosition. (patchset #6 id:100001 of
https://codereview.chromium.org/2383113003/ )

Reason for revert:
Blocks revert of another patch: https://codereview.chromium.org/2395683002/

Original issue's description:
> Refactor ScrollableArea::setScrollPosition.
> 
> - Eliminate some redundant PaintLayerScrollableArea methods and
> indirection.
> 
> - ScrollableArea::setScrollPosition now always clamps its argument.
> Code inspection revealed that nearly all callers were clamping
> the position argument anyway.
> 
> - ScrollableArea::setScrollPosition returns immediately if the scroll
> position did not change.  This avoids a bunch of unnecessary
> work.
> 
> - For the rare instances where the scroll position should not be
> clamped, or the scroll position update code should run even if the
> scroll position didn't change, add the method
> setScrollPositionUnconditionally.
> 
> - When modifying the scroll position due to a change in effective
> zoom, preserve the offset from beginning of flow, rather than the
> distance from top-left of overflow area.
> 
> BUG=417782
> R=skobes@chromium.org,bokan@chromium.org
>
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2
> 
> Committed: https://crrev.com/cddc823c56d453758003a831fd5a2475e94c0387
> Cr-Commit-Position: refs/heads/master@{#423033}

TBR=bokan@chromium.org,skobes@chromium.org,pdr@chromium.org,szager@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=417782
==========

to

==========
Revert of Refactor ScrollableArea::setScrollPosition. (patchset #6 id:100001 of
https://codereview.chromium.org/2383113003/ )

Reason for revert:
Blocks revert of another patch: https://codereview.chromium.org/2395683002/

Original issue's description:
> Refactor ScrollableArea::setScrollPosition.
>
> - Eliminate some redundant PaintLayerScrollableArea methods and
> indirection.
>
> - ScrollableArea::setScrollPosition now always clamps its argument.
> Code inspection revealed that nearly all callers were clamping
> the position argument anyway.
>
> - ScrollableArea::setScrollPosition returns immediately if the scroll
> position did not change.  This avoids a bunch of unnecessary
> work.
>
> - For the rare instances where the scroll position should not be
> clamped, or the scroll position update code should run even if the
> scroll position didn't change, add the method
> setScrollPositionUnconditionally.
>
> - When modifying the scroll position due to a change in effective
> zoom, preserve the offset from beginning of flow, rather than the
> distance from top-left of overflow area.
>
> BUG=417782
> R=skobes@chromium.org,bokan@chromium.org
>
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2
>
> Committed: https://crrev.com/cddc823c56d453758003a831fd5a2475e94c0387
> Cr-Commit-Position: refs/heads/master@{#423033}

TBR=bokan@chromium.org,skobes@chromium.org,pdr@chromium.org,szager@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=417782

Committed: https://crrev.com/6df05cf7d1cf36aa01a45db245093eab3c8bca0e
Cr-Commit-Position: refs/heads/master@{#423041}
==========

[commit-bot: I haz the power, 2016-10-05 01:33:48]

Patchset 1 (id:??) landed as
https://crrev.com/6df05cf7d1cf36aa01a45db245093eab3c8bca0e
Cr-Commit-Position: refs/heads/master@{#423041}