In step (4), after unminimizing chrome window, window state is fullscreen (but tabstrip is still visible so it looks like maximized state instead). Stack trace: https://paste.googleplex.com/6339951239102464

Is fullscreen window state type expected in step (4)?

Yes I think we're using fullscreen state to hide the title bar. +Sammie

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/526cc33b6e631f8b02daac102a91111462143914

commit 526cc33b6e631f8b02daac102a91111462143914
Author: Qiang Xu <warx@google.com>
Date: Wed Mar 21 19:00:01 2018

cros: do not clear kPreMinimizedShowStateKey in tablet mode

changes:
Do not clear kPreMinimizedShowStateKey in tablet mode, instead let it
persist before/after tablet mode.

Bug:  823175 ,  783310 
Test: manual test and added test coverage.
Change-Id: Icec1675da9c7d1b5b955ae5c05a71d96547afeee
Reviewed-on: https://chromium-review.googlesource.com/969455
Reviewed-by: Scott Violet <sky@chromium.org>
Commit-Queue: Qiang Xu <warx@google.com>
Cr-Commit-Position: refs/heads/master@{#544789}
[modify] https://crrev.com/526cc33b6e631f8b02daac102a91111462143914/ash/wm/tablet_mode/tablet_mode_window_manager_unittest.cc
[modify] https://crrev.com/526cc33b6e631f8b02daac102a91111462143914/ash/wm/window_state.cc
[modify] https://crrev.com/526cc33b6e631f8b02daac102a91111462143914/ui/wm/core/window_util.cc

Re #2, I saw currently packaged apps (files) and android apps will hide title bar, but browser window is not. Is this also expected UX behavior?

Re #2, its supposed to use maximized state, and hide the title bar in custom_frame_view_ash, at least for chrome v1 and v2 apps. I'm not sure about arc apps, i think they use fullscreen state for maximized though.

re #4, yeah the browser does not hide title bar is expected, as it contains the tabs which still need to be there.

Thanks for explaining. For #2, I once logged a fullscreen state. I will file a bug when I had a chance to get it logged again.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/d0b6126a6bcab9531ec25851e56d2976a495ab96

commit d0b6126a6bcab9531ec25851e56d2976a495ab96
Author: Qiang Xu <warx@google.com>
Date: Mon Mar 26 16:42:56 2018

m66 merge: cros: do not clear kPreMinimizedShowStateKey in tablet mode

changes:
Do not clear kPreMinimizedShowStateKey in tablet mode, instead let it
persist before/after tablet mode.

TBR=sky@chromium.org

(cherry picked from commit 526cc33b6e631f8b02daac102a91111462143914)

Bug:  823175 ,  783310 
Test: manual test and added test coverage.
Change-Id: Icec1675da9c7d1b5b955ae5c05a71d96547afeee
Reviewed-on: https://chromium-review.googlesource.com/969455
Reviewed-by: Scott Violet <sky@chromium.org>
Commit-Queue: Qiang Xu <warx@google.com>
Cr-Original-Commit-Position: refs/heads/master@{#544789}
Reviewed-on: https://chromium-review.googlesource.com/980794
Reviewed-by: Qiang Xu <warx@google.com>
Cr-Commit-Position: refs/branch-heads/3359@{#432}
Cr-Branched-From: 66afc5e5d10127546cc4b98b9117aff588b5e66b-refs/heads/master@{#540276}
[modify] https://crrev.com/d0b6126a6bcab9531ec25851e56d2976a495ab96/ash/wm/tablet_mode/tablet_mode_window_manager_unittest.cc
[modify] https://crrev.com/d0b6126a6bcab9531ec25851e56d2976a495ab96/ash/wm/window_state.cc
[modify] https://crrev.com/d0b6126a6bcab9531ec25851e56d2976a495ab96/ui/wm/core/window_util.cc