and in this state, if you extract the tab by dragging, it still say you can't snap the window, but dragging to scrim does respond.

sorry, it was by mistake.

I think it may related to the device scale you're using. If you use a big device scale, the minimum window width (in landscape) is bigger than 1/2 of the screen width, thus can't be snapped.

We just tried on Dru with a smaller device scale (using ctl+shift+- to decrease it), it works fine.

But I think the behavior in #1 still needs to be fixed.

Thanks. Going to fix the issue at #1.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/104b5d40974be1355bcbf1a495afbfd3d6da0a73

commit 104b5d40974be1355bcbf1a495afbfd3d6da0a73
Author: Min Chen <minch@google.com>
Date: Tue Nov 27 01:07:38 2018

Tab dragging: None snap position if dragged window can't be snapped.

Should consider whether the dragged window can be snapped when trying
to get the snap position on the drag position. Then in multi-tabs drag,
drag one tab out of the source window will not put the source window to
the snapped window's position during drag. Note, browser window may
can't be snapped on different display bounds or scales.

Bug: 905924
Change-Id: I9166092af4252ca44b221da082be1fdb0297f034
Reviewed-on: https://chromium-review.googlesource.com/c/1345425
Reviewed-by: Mitsuru Oshima <oshima@chromium.org>
Commit-Queue: Min Chen <minch@chromium.org>
Cr-Commit-Position: refs/heads/master@{#610987}
[modify] https://crrev.com/104b5d40974be1355bcbf1a495afbfd3d6da0a73/ash/wm/splitview/split_view_controller_unittest.cc
[modify] https://crrev.com/104b5d40974be1355bcbf1a495afbfd3d6da0a73/ash/wm/tablet_mode/tablet_mode_window_drag_delegate.cc

For the issue in the description that browser window in Dru can't be snapped in landscape. It is because of the minimum size of the browser window. Its minimum size is larger than half of the width of the display with default scale of Dru. Feel it is kind of weird in this case. Ben, Omri, do you have any idea of what it should be in this case?
Feel it is kind of similar as the issue 897380, both because of the minimum size of the browser window.

I was going to file the same issue today, but it looks like it's (mostly) fixed in dev channel?

With new small devices we should make sure browser supports at least the 50/50 split, but I want to work on better super-narrow designs in 2019 to support 1/3 splits on 10" tablets and 50/50 on 8".

The issue is that browser has a minimum size, based on the UI elements on the browser frame, which can exceeds the 1/2 of the screen width. We shouldn't just ignore it because it can break layout. For short term, we can remove home button (who uses it nowaways?) and replace reload button with reload gesture in tablet mode, or splitscreen at least.