Hi Ben, from the second screenshot, the position of the drag indicator is not correct, I can go to fix it.

For the first screenshot, do you mean that the drag indicator should not have overlap with the shelf? How about after dragged the window into the drag indicator and show the preview area (the area of dragged window where it will be snapped)？ Should it have overlap with the shelf? If not, then where should the dragged window be snapped after drag finished? Should it be covered by the auto-hide-shown shelf or just the same as "always shown" shelf? 

Thanks for filing this Ben. Since auto-hide shelf is always shown in splitscreen and tablet mode. Do you mean just treat it as "always shown" shelf? Then, the drag indicator size and position, the bounds of the snapped window will just the same for "auto-hide" and "always show" shelf. Is this what we want? Thanks.

Hey Min, re #2, yes. I'm saying both the indicator and preview area size and positions should be the same, regardless of shelf state. This shouldn't affect snap sizes though, which should still target the full screen height / width layered below the shelf when shelf is set to "autohide".

"tablet mode" in #2 should be "overview mode".
Hi Ben, if we keep the indicator and preview area bounds the same regardless of the shelf state (always no overlap with the shelf). Since preview area means where the dragged window will be snapped, it should equal to the snap bounds. If we only change the logic for preview area but keep the logic of snap bounds (still need to consider the shelf state). Then, for auto-hide shelf, the preview area bounds of the dragged window will be different with its final snap bounds. It sounds kind of weird to me based on this point.

Hi Ben, I took a video here
https://drive.google.com/file/d/0B5I0jFeLxqIiNEVKZHVPeFhXMkdBcDBneFVGbVppbzJSTjFR/view?usp=sharing

For auto-hide shelf, even though the preview area and final snap bounds are different. But I agree that it looks better to make sure preview area has no overlap with the shelf. Let me know if what in the video is what we want or sth else I need to change. Thanks.

Hey Min, sorry for the delayed response. Yes, snap bounds and preview area different. The video looks great! It did demonstrate an unrelated issue, though - the shelf should change to the fullscreen opaque shelf without rounded corners after the first app is snapped. I don't know how long it's been like this, but it was something we fixed once before for the original splitscreen launch.

Thanks Ben. For the shelf rounded corners issue I will go to file another bug for it.

Awesome, thanks Min!

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/10d413c5cc8a8b471a303e0168d947732f6a1369

commit 10d413c5cc8a8b471a303e0168d947732f6a1369
Author: Min Chen <minch@google.com>
Date: Fri Dec 07 01:27:36 2018

Make splitview drag indicators always have no overlap with shelf.

See recorded video:
https://drive.google.com/file/d/0B5I0jFeLxqIiR3dNb1M4andpb3FnZUtCMVR1VkFSa1NhaURz/view?usp=sharing

Bug:  908686 
Change-Id: Id9ef51dfa6e399638a328bed6511036335a2c0c5
Reviewed-on: https://chromium-review.googlesource.com/c/1364470
Reviewed-by: Xiaoqian Dai <xdai@chromium.org>
Commit-Queue: Min Chen <minch@chromium.org>
Cr-Commit-Position: refs/heads/master@{#614560}
[modify] https://crrev.com/10d413c5cc8a8b471a303e0168d947732f6a1369/ash/wm/splitview/split_view_drag_indicators.cc
[modify] https://crrev.com/10d413c5cc8a8b471a303e0168d947732f6a1369/ash/wm/splitview/split_view_drag_indicators.h