Prevent create ScrollbarAnimationController for Mac Overlay Scrollbar

Prevent create ScrollbarAnimationController for Mac Overlay Scrollbar

crbug.com/724507 is caused by my patch
(crrev.com/b50f6446eb79c4aaaac0a5eefdf90d2b4a99ce54). I assigned
`settings.scrollbar_animator = cc::LayerTreeSettings::ANDROID_OVERLAY`
for default which we assigned `LayerTreeSettings::NO_ANIMATOR` before.
Which can give mobile emulator correct settings but in
LayerTreeImpl::RegisterScrollbar -
LayerTreeHostImpl::RegisterScrollbarAnimationController we create
ScrollbarAnimationController to handle scrollbar's opacity.

In this patch, we add GetScrollbarAnimator to ScrollbarLayerImplBase
and its subclasses. PaintedScrollbarLayerImpl::GetScrollbarAnimator can
always returns NO_ANIMATOR because AuraOverlayScrollbar is using
PaintedOverlayScrollbarLayerImpl, others can return based on
LayerTreeSettings. Then we can prevent create
ScrollbarAnimationController for Mac Overlay Scrollbar by checking
scrollbar's animator.

BUG=724507
CQ_INCLUDE_TRYBOTS=master.tryserver.blink:linux_trusty_blink_rel

Review-Url: https://codereview.chromium.org/2918753002
Cr-Original-Commit-Position: refs/heads/master@{#477287}
Review-Url: https://codereview.chromium.org/2930763002 .
Cr-Commit-Position: refs/branch-heads/3112@{#227}
Cr-Branched-From: b6460e24cf59f429d69de255538d0fc7a425ccf9-refs/heads/master@{#474897}
Committed: https://chromium.googlesource.com/chromium/src/+/4ed7edd91d41218b4f7c4786782164b20a48ab04

[bokan, 2017-06-07 18:49:50]

Description was changed from

==========
Prevent create ScrollbarAnimationController for Mac Overlay Scrollbar

crbug.com/724507 is caused by my patch
(crrev.com/b50f6446eb79c4aaaac0a5eefdf90d2b4a99ce54). I assigned
`settings.scrollbar_animator = cc::LayerTreeSettings::ANDROID_OVERLAY`
for default which we assigned `LayerTreeSettings::NO_ANIMATOR` before.
Which can give mobile emulator correct settings but in
LayerTreeImpl::RegisterScrollbar -
LayerTreeHostImpl::RegisterScrollbarAnimationController we create
ScrollbarAnimationController to handle scrollbar's opacity.

In this patch, we add GetScrollbarAnimator to ScrollbarLayerImplBase
and its subclasses. PaintedScrollbarLayerImpl::GetScrollbarAnimator can
always returns NO_ANIMATOR because AuraOverlayScrollbar is using
PaintedOverlayScrollbarLayerImpl, others can return based on
LayerTreeSettings. Then we can prevent create
ScrollbarAnimationController for Mac Overlay Scrollbar by checking
scrollbar's animator.

BUG=724507
CQ_INCLUDE_TRYBOTS=master.tryserver.blink:linux_trusty_blink_rel

Review-Url: https://codereview.chromium.org/2918753002
Cr-Commit-Position: refs/heads/master@{#477287}
(cherry picked from commit 4795906652460b283e526e6745057d77f0133980)
==========

to

==========
Prevent create ScrollbarAnimationController for Mac Overlay Scrollbar

crbug.com/724507 is caused by my patch
(crrev.com/b50f6446eb79c4aaaac0a5eefdf90d2b4a99ce54). I assigned
`settings.scrollbar_animator = cc::LayerTreeSettings::ANDROID_OVERLAY`
for default which we assigned `LayerTreeSettings::NO_ANIMATOR` before.
Which can give mobile emulator correct settings but in
LayerTreeImpl::RegisterScrollbar -
LayerTreeHostImpl::RegisterScrollbarAnimationController we create
ScrollbarAnimationController to handle scrollbar's opacity.

In this patch, we add GetScrollbarAnimator to ScrollbarLayerImplBase
and its subclasses. PaintedScrollbarLayerImpl::GetScrollbarAnimator can
always returns NO_ANIMATOR because AuraOverlayScrollbar is using
PaintedOverlayScrollbarLayerImpl, others can return based on
LayerTreeSettings. Then we can prevent create
ScrollbarAnimationController for Mac Overlay Scrollbar by checking
scrollbar's animator.

BUG=724507
CQ_INCLUDE_TRYBOTS=master.tryserver.blink:linux_trusty_blink_rel

Review-Url: https://codereview.chromium.org/2918753002
Cr-Original-Commit-Position: refs/heads/master@{#477287}
Review-Url: https://codereview.chromium.org/2930763002 .
Cr-Commit-Position: refs/branch-heads/3112@{#227}
Cr-Branched-From:
b6460e24cf59f429d69de255538d0fc7a425ccf9-refs/heads/master@{#474897}
Committed:
https://chromium.googlesource.com/chromium/src/+/4ed7edd91d41218b4f7c47867821...
==========

[bokan, 2017-06-07 18:49:52]

Committed patchset #1 (id:1) manually as
4ed7edd91d41218b4f7c4786782164b20a48ab04.