Revert of Fade out overlay scrollbar after page load

Revert of Fade out overlay scrollbar after page load (patchset #1 id:1 of https://codereview.chromium.org/2858973002/ )

Reason for revert:
Revert for regression

Details: https://bugs.chromium.org/p/chromium/issues/detail?id=718863

Original issue's description:
> Fade out overlay scrollbar after page load
> 
> This issue is caused by Aura Overlay Scrollbar is created with
> opacity>0. We
> used to call SAC::DidScrollUpdate - LTI::UpdateScrollbars to fade out
> when RegisterScrollLayer.
> 
> 
> ```
> #2 0x7f23d0dfe1ea cc::LayerTreeImpl::UpdateScrollbars()
> #3 0x7f23d0dfd999 cc::LayerTreeImpl::DidUpdateScrollState()
> #4 0x7f23d0e07231 cc::LayerTreeImpl::RegisterScrollLayer()
> ```
> 
> But we remove ScrollbarAnimationController::DidScrollUpdate call in
> UpdateScrollbars at
> https://crrev.com/697a467f819ce09da5209a3df13b8b92f33e35a4.
> Then Overlay Scrollbar can not fade out until we have real scroll.
> 
> In this patch, we apply set_needs_show_scrollbars(true) to the layer in
> LayerTreeImpl::RegisterScrollLayer that will let
> LTI::HandleScrollbarShowRequestsFromMain pickup and call
> SAC::DidScrollUpdate.
> 
> For cc_unittest, remove set_needs_show_scrollbars call in
> LayerTreeHostImplTestScrollbarAnimation.* and
> LayerTreeHostImplTest.ScrollbarVisibilityChangeCausesRedrawAndCommit.
> 
> BUG=717222
> CQ_INCLUDE_TRYBOTS=master.tryserver.blink:linux_trusty_blink_rel
> 
> Review-Url: https://codereview.chromium.org/2858973002
> Cr-Commit-Position: refs/heads/master@{#469425}
> Committed: https://chromium.googlesource.com/chromium/src/+/b14926c905396fbeb0a77bfc6cce569c8a35fa5f

TBR=weiliangc@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=717222
Review-Url: https://codereview.chromium.org/2863153002
Cr-Commit-Position: refs/heads/master@{#469763}
Committed: https://chromium.googlesource.com/chromium/src/+/9320fa40f77c26a054be97c9e2c7543e277c3081

[chaopeng, 2017-05-05 18:06:48]

The CQ bit was checked by chaopeng@chromium.org

[chaopeng, 2017-05-05 18:06:49]

Created Revert of Fade out overlay scrollbar after page load

[commit-bot: I haz the power, 2017-05-05 18:07:20]

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, 2017-05-05 18:07:21]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2017-05-05 18:07:22]

No L-G-T-M from a valid reviewer yet.
CQ run can only be started once the patch has received an L-G-T-M from a full
committer.
Even if an L-G-T-M may have been provided, it was from a non-committer,_not_ a
full super star committer.
Committers are members of the group "project-chromium-committers".
Note that this has nothing to do with OWNERS files.

[chaopeng, 2017-05-05 18:08:31]

weiliangc@ Please stamp for revert. Thank you.

[weiliangc, 2017-05-05 20:05:44]

The CQ bit was checked by weiliangc@chromium.org

[weiliangc, 2017-05-05 20:05:45]

lgtm

[commit-bot: I haz the power, 2017-05-05 20:06:37]

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, 2017-05-05 20:07:06]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1494014744996890, "parent_rev":
"948b7d3d9c386168859282feb18a64f9f99327c4", "commit_rev":
"9320fa40f77c26a054be97c9e2c7543e277c3081"}

[commit-bot: I haz the power, 2017-05-05 20:07:16]

Description was changed from

==========
Revert of Fade out overlay scrollbar after page load (patchset #1 id:1 of
https://codereview.chromium.org/2858973002/ )

Reason for revert:
Revert for regression

Details: https://bugs.chromium.org/p/chromium/issues/detail?id=718863

Original issue's description:
> Fade out overlay scrollbar after page load
> 
> This issue is caused by Aura Overlay Scrollbar is created with
> opacity>0. We
> used to call SAC::DidScrollUpdate - LTI::UpdateScrollbars to fade out
> when RegisterScrollLayer.
> 
> 
> ```
> #2 0x7f23d0dfe1ea cc::LayerTreeImpl::UpdateScrollbars()
> #3 0x7f23d0dfd999 cc::LayerTreeImpl::DidUpdateScrollState()
> #4 0x7f23d0e07231 cc::LayerTreeImpl::RegisterScrollLayer()
> ```
> 
> But we remove ScrollbarAnimationController::DidScrollUpdate call in
> UpdateScrollbars at
> https://crrev.com/697a467f819ce09da5209a3df13b8b92f33e35a4.
> Then Overlay Scrollbar can not fade out until we have real scroll.
> 
> In this patch, we apply set_needs_show_scrollbars(true) to the layer in
> LayerTreeImpl::RegisterScrollLayer that will let
> LTI::HandleScrollbarShowRequestsFromMain pickup and call
> SAC::DidScrollUpdate.
> 
> For cc_unittest, remove set_needs_show_scrollbars call in
> LayerTreeHostImplTestScrollbarAnimation.* and
> LayerTreeHostImplTest.ScrollbarVisibilityChangeCausesRedrawAndCommit.
> 
> BUG=717222
> CQ_INCLUDE_TRYBOTS=master.tryserver.blink:linux_trusty_blink_rel
> 
> Review-Url: https://codereview.chromium.org/2858973002
> Cr-Commit-Position: refs/heads/master@{#469425}
> Committed:
https://chromium.googlesource.com/chromium/src/+/b14926c905396fbeb0a77bfc6cce...

TBR=weiliangc@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=717222
==========

to

==========
Revert of Fade out overlay scrollbar after page load (patchset #1 id:1 of
https://codereview.chromium.org/2858973002/ )

Reason for revert:
Revert for regression

Details: https://bugs.chromium.org/p/chromium/issues/detail?id=718863

Original issue's description:
> Fade out overlay scrollbar after page load
> 
> This issue is caused by Aura Overlay Scrollbar is created with
> opacity>0. We
> used to call SAC::DidScrollUpdate - LTI::UpdateScrollbars to fade out
> when RegisterScrollLayer.
> 
> 
> ```
> #2 0x7f23d0dfe1ea cc::LayerTreeImpl::UpdateScrollbars()
> #3 0x7f23d0dfd999 cc::LayerTreeImpl::DidUpdateScrollState()
> #4 0x7f23d0e07231 cc::LayerTreeImpl::RegisterScrollLayer()
> ```
> 
> But we remove ScrollbarAnimationController::DidScrollUpdate call in
> UpdateScrollbars at
> https://crrev.com/697a467f819ce09da5209a3df13b8b92f33e35a4.
> Then Overlay Scrollbar can not fade out until we have real scroll.
> 
> In this patch, we apply set_needs_show_scrollbars(true) to the layer in
> LayerTreeImpl::RegisterScrollLayer that will let
> LTI::HandleScrollbarShowRequestsFromMain pickup and call
> SAC::DidScrollUpdate.
> 
> For cc_unittest, remove set_needs_show_scrollbars call in
> LayerTreeHostImplTestScrollbarAnimation.* and
> LayerTreeHostImplTest.ScrollbarVisibilityChangeCausesRedrawAndCommit.
> 
> BUG=717222
> CQ_INCLUDE_TRYBOTS=master.tryserver.blink:linux_trusty_blink_rel
> 
> Review-Url: https://codereview.chromium.org/2858973002
> Cr-Commit-Position: refs/heads/master@{#469425}
> Committed:
https://chromium.googlesource.com/chromium/src/+/b14926c905396fbeb0a77bfc6cce...

TBR=weiliangc@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=717222

Review-Url: https://codereview.chromium.org/2863153002
Cr-Commit-Position: refs/heads/master@{#469763}
Committed:
https://chromium.googlesource.com/chromium/src/+/9320fa40f77c26a054be97c9e2c7...
==========

[commit-bot: I haz the power, 2017-05-05 20:07:18]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/chromium/src/+/9320fa40f77c26a054be97c9e2c7...