The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/16869bea5ed795110e0d273295de03dcaa067800

commit 16869bea5ed795110e0d273295de03dcaa067800
Author: Sammie Quon <sammiequon@google.com>
Date: Fri Feb 16 02:59:33 2018

splitview: Animate phantom windows p1.

spec: https://mccanny.users.x20web.corp.google.com/www/splitscreen-motion/index.html

The attached spec wants phantom windows to animate out from the "Drag window here"
indicators. This changes phantom windows from being a separate widget to being part
of the same widget which controls the splitview text. This will allow the animations
in the spec to happen.

The phantom windows are now part of those highlights which are part of the splitview
text. When an item reaches the phantom threshold, the highlight will expand and the
text will disappear. There is some difficult getting the phantom windows to have
rounded corners like they should, but the old ones did not either, so I think it is
ok for now.

The highlights and text layers have their transform and opacity altered rather than
using SetBounds or SetVisible so it will be easier to animate in a follow up cl.

Manually tested using all orientations and multiple divider positions.

Test: ash_unittests SplitViewWindowSelectorTest.*
Bug:  808283 
Change-Id: I4b61e5dce394ac05abd4038aee3a07067727f625
Reviewed-on: https://chromium-review.googlesource.com/898247
Reviewed-by: Mitsuru Oshima (In Tokyo) <oshima@chromium.org>
Reviewed-by: Xiaoqian Dai <xdai@chromium.org>
Commit-Queue: Sammie Quon <sammiequon@chromium.org>
Cr-Commit-Position: refs/heads/master@{#537160}
[modify] https://crrev.com/16869bea5ed795110e0d273295de03dcaa067800/ash/wm/overview/overview_window_drag_controller.cc
[modify] https://crrev.com/16869bea5ed795110e0d273295de03dcaa067800/ash/wm/overview/overview_window_drag_controller.h
[modify] https://crrev.com/16869bea5ed795110e0d273295de03dcaa067800/ash/wm/overview/rounded_rect_view.cc
[modify] https://crrev.com/16869bea5ed795110e0d273295de03dcaa067800/ash/wm/overview/rounded_rect_view.h
[modify] https://crrev.com/16869bea5ed795110e0d273295de03dcaa067800/ash/wm/overview/window_selector.cc
[modify] https://crrev.com/16869bea5ed795110e0d273295de03dcaa067800/ash/wm/overview/window_selector.h
[modify] https://crrev.com/16869bea5ed795110e0d273295de03dcaa067800/ash/wm/overview/window_selector_unittest.cc
[modify] https://crrev.com/16869bea5ed795110e0d273295de03dcaa067800/ash/wm/splitview/split_view_overview_overlay.cc
[modify] https://crrev.com/16869bea5ed795110e0d273295de03dcaa067800/ash/wm/splitview/split_view_overview_overlay.h

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/8250507fce543357e051cbd9bcf0573bd3c25991

commit 8250507fce543357e051cbd9bcf0573bd3c25991
Author: Sammie Quon <sammiequon@google.com>
Date: Fri Feb 23 00:08:28 2018

splitview: Animate phantom windows p2.

spec: https://mccanny.users.x20web.corp.google.com/www/splitscreen-motion/index.html

Performs the animations after the setup in p1.

I held off shifting the text label back and forth as the spec states
because there is already a transform on it (to rotate the label). Perhaps
animating the bounds would work, but some math would be required to do that.

Test: manual
Bug:  808283 
Change-Id: If315601c63f4d8850e026eecffb390de3096fee7
Reviewed-on: https://chromium-review.googlesource.com/900484
Reviewed-by: Mitsuru Oshima <oshima@chromium.org>
Reviewed-by: Xiaoqian Dai <xdai@chromium.org>
Commit-Queue: Sammie Quon <sammiequon@chromium.org>
Cr-Commit-Position: refs/heads/master@{#538628}
[modify] https://crrev.com/8250507fce543357e051cbd9bcf0573bd3c25991/ash/wm/overview/window_selector_item.cc
[modify] https://crrev.com/8250507fce543357e051cbd9bcf0573bd3c25991/ash/wm/splitview/split_view_overview_overlay.cc
[modify] https://crrev.com/8250507fce543357e051cbd9bcf0573bd3c25991/ash/wm/splitview/split_view_utils.cc
[modify] https://crrev.com/8250507fce543357e051cbd9bcf0573bd3c25991/ash/wm/splitview/split_view_utils.h

+oshima

Oshima mentioned renaming phantom window and overview overlay in cl 1.

How does

phantom window -> splitview preview area
overview overlay -> splitview drag indicators

sound?

xdai any suggestions?

Sounds good to me.

oops forgot to add +oshima

oshima what do you think of the suggestions in #4

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/59159caab58eb9232c6b4a35ee8f07e8de036d96

commit 59159caab58eb9232c6b4a35ee8f07e8de036d96
Author: Sammie Quon <sammiequon@google.com>
Date: Thu Mar 01 06:05:14 2018

splitview: Animate phantom windows p3.

Preserve round edges after animation. Calculates the bounds after animation
and applies identity transform.

Test: manual
Bug:  808283 
Change-Id: I8370f63983bf3fd568d7cb5712e7cd09e380edeb
Reviewed-on: https://chromium-review.googlesource.com/940568
Commit-Queue: Sammie Quon <sammiequon@chromium.org>
Reviewed-by: Xiaoqian Dai <xdai@chromium.org>
Reviewed-by: Mitsuru Oshima <oshima@chromium.org>
Cr-Commit-Position: refs/heads/master@{#540068}
[modify] https://crrev.com/59159caab58eb9232c6b4a35ee8f07e8de036d96/ash/wm/splitview/split_view_overview_overlay.cc

#6, sgtm

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/be8f7b095ed9bba9830783a4297fbf30f4ad4f1d

commit be8f7b095ed9bba9830783a4297fbf30f4ad4f1d
Author: Sammie Quon <sammiequon@google.com>
Date: Wed Mar 14 02:08:17 2018

splitview: Rename phantom windows and overlay to more specific.

Phantom window and overlay have other meanings for other uses.

Phantom windows -> preview area as it is a highlight which gives a preview
of the bounds of a snapped window.
Overlay -> drag indicators. The class handles displaying various indications
for entering split view.

Test: ash_unittests SplitViewWindowSelectorTest.*
Bug:  808283 
Change-Id: If8bb36792daa7d89c8dac96cc5baf841bee3bdee
Reviewed-on: https://chromium-review.googlesource.com/946887
Commit-Queue: Sammie Quon <sammiequon@chromium.org>
Reviewed-by: Xiaoqian Dai <xdai@chromium.org>
Reviewed-by: Mitsuru Oshima <oshima@chromium.org>
Cr-Commit-Position: refs/heads/master@{#542984}
[modify] https://crrev.com/be8f7b095ed9bba9830783a4297fbf30f4ad4f1d/ash/BUILD.gn
[modify] https://crrev.com/be8f7b095ed9bba9830783a4297fbf30f4ad4f1d/ash/wm/overview/overview_window_drag_controller.cc
[modify] https://crrev.com/be8f7b095ed9bba9830783a4297fbf30f4ad4f1d/ash/wm/overview/overview_window_drag_controller.h
[modify] https://crrev.com/be8f7b095ed9bba9830783a4297fbf30f4ad4f1d/ash/wm/overview/window_selector.cc
[modify] https://crrev.com/be8f7b095ed9bba9830783a4297fbf30f4ad4f1d/ash/wm/overview/window_selector.h
[modify] https://crrev.com/be8f7b095ed9bba9830783a4297fbf30f4ad4f1d/ash/wm/overview/window_selector_unittest.cc
[rename] https://crrev.com/be8f7b095ed9bba9830783a4297fbf30f4ad4f1d/ash/wm/splitview/split_view_drag_indicators.cc
[rename] https://crrev.com/be8f7b095ed9bba9830783a4297fbf30f4ad4f1d/ash/wm/splitview/split_view_drag_indicators.h
[modify] https://crrev.com/be8f7b095ed9bba9830783a4297fbf30f4ad4f1d/ash/wm/splitview/split_view_utils.cc
[modify] https://crrev.com/be8f7b095ed9bba9830783a4297fbf30f4ad4f1d/ash/wm/splitview/split_view_utils.h

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/e61bdc1e8a71cd3e4796cbfc494438372d41e12d

commit e61bdc1e8a71cd3e4796cbfc494438372d41e12d
Author: Sammie Quon <sammiequon@google.com>
Date: Sat Mar 17 02:05:54 2018

splitview: Animate split view indicators p4.

Last one of spec. Animates the "drag to use splitview" labels (slide in
and out and also fade in and out). Create a new child view, which is the
one which will get a rotation transform. The parent view will be the
layer that gets translated.

Note: p1 p2 p3 are called "splitview: Animate phantom window".

Test: manual
Bug:  808283 
Change-Id: I95e1cef7056c1ab4272c05fc8a1a32187576e6bd
Reviewed-on: https://chromium-review.googlesource.com/961497
Reviewed-by: Xiaoqian Dai <xdai@chromium.org>
Commit-Queue: Sammie Quon <sammiequon@chromium.org>
Cr-Commit-Position: refs/heads/master@{#543914}
[modify] https://crrev.com/e61bdc1e8a71cd3e4796cbfc494438372d41e12d/ash/wm/splitview/split_view_drag_indicators.cc
[modify] https://crrev.com/e61bdc1e8a71cd3e4796cbfc494438372d41e12d/ash/wm/splitview/split_view_utils.cc
[modify] https://crrev.com/e61bdc1e8a71cd3e4796cbfc494438372d41e12d/ash/wm/splitview/split_view_utils.h