How do we identify tablet mode?

Also, shouldn't a user be able to change the orientation of their desktop?

> How do we identify tablet mode?
In c++, it's MaximiezModeController::IsMaximizeModeWindowManagerEnabled()

not sure what's the best way to hook this up on js side. We probably can add it to display api.

> Also, shouldn't a user be able to change the orientation of their desktop?
A user can rotate the device to change the orientation, but it may not rotate if an application locked the orientation.

Is this something we need for 58, or is 59 OK given that we are just trying to reduce confusion, not change functionality?

If it's risky to merge, 59 is ok.

I'm not marking this as a launch-blocker for MD Settings since we would launch in M59 without this. Please let me know if you disagree.

Two questions:

1) I assume MaximiezModeController::IsMaximizeModeWindowManagerEnabled() only applies when there is a single display?

2) Can that change dynamically? If so, what should be observed and how?

1) I assume MaximiezModeController::IsMaximizeModeWindowManagerEnabled() only 
applies when there is a single display?

Unfortunately, no. Ideally, we should disable only for internal display, but I think just disabling globally is fine.

2) ShellObserver has these methods.

https://cs.chromium.org/chromium/src/ash/shell_observer.h?rcl=7735ed2d044b9afaa1c853f003084a55e6c6e42a&l=61

OK, I am looking at how best to trigger a chrome.system.display.onDisplayChanged() event for when IsMaximizeModeWindowManagerEnabled() changes.

src/extensions does not currently depend on ash, and it probably shouldn't, so I can't make SystemInfoEventRouter an ash::ShellObserver.

SystemInfoEventRouter is however already a display::DisplayObserver.

I am thinking of having Shell::NotifyMaximizeModeStarted/Ended also call display_manager_->NotifyMetricsChanged(display_manager_->GetPrimaryDisplayCandidat(), DisplayObserver::DISPLAY_METRIC_MAXIMIZE_MODE);

WDYT?

#8 agreed. This isn't critical, and we can punt this to 60.

I put up a CL for this here:
https://codereview.chromium.org/2824843002/

But am waiting on some changes by oshima@ per comment in the CL.

Can you go ahead and reassign this to me when the display manager changes are ready (and what to call from the UI)?

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/f597670d9a6ea1298dac6048389c3a51e45d6434

commit f597670d9a6ea1298dac6048389c3a51e45d6434
Author: oshima <oshima@chromium.org>
Date: Thu Jun 22 22:17:46 2017

Add accelerometer support property to Display.

BUG= 704929 
TEST=covered by unit test

Review-Url: https://codereview.chromium.org/2950083002
Cr-Commit-Position: refs/heads/master@{#481690}

[modify] https://crrev.com/f597670d9a6ea1298dac6048389c3a51e45d6434/ash/display/display_manager_unittest.cc
[modify] https://crrev.com/f597670d9a6ea1298dac6048389c3a51e45d6434/ash/display/screen_ash.cc
[modify] https://crrev.com/f597670d9a6ea1298dac6048389c3a51e45d6434/ui/display/display.h
[modify] https://crrev.com/f597670d9a6ea1298dac6048389c3a51e45d6434/ui/display/manager/display_manager.cc
[modify] https://crrev.com/f597670d9a6ea1298dac6048389c3a51e45d6434/ui/display/manager/display_manager.h

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/f642949fc45c792e93e4e9ad1f1f489097ae73a0

commit f642949fc45c792e93e4e9ad1f1f489097ae73a0
Author: kylechar <kylechar@chromium.org>
Date: Mon Jun 26 16:37:50 2017

Add AccelerometerSupport to Display StructTraits.

Also small cleanup in DisplayStructTraitsTests.

Bug:  704929 
Change-Id: I00c69a7fb7209554489409c5d016688da386cbc6
Reviewed-on: https://chromium-review.googlesource.com/546619
Commit-Queue: kylechar <kylechar@chromium.org>
Reviewed-by: Tom Sepez <tsepez@chromium.org>
Reviewed-by: Mitsuru Oshima <oshima@chromium.org>
Cr-Commit-Position: refs/heads/master@{#482291}
[modify] https://crrev.com/f642949fc45c792e93e4e9ad1f1f489097ae73a0/ui/display/mojo/display.mojom
[modify] https://crrev.com/f642949fc45c792e93e4e9ad1f1f489097ae73a0/ui/display/mojo/display.typemap
[modify] https://crrev.com/f642949fc45c792e93e4e9ad1f1f489097ae73a0/ui/display/mojo/display_struct_traits.cc
[modify] https://crrev.com/f642949fc45c792e93e4e9ad1f1f489097ae73a0/ui/display/mojo/display_struct_traits.h
[modify] https://crrev.com/f642949fc45c792e93e4e9ad1f1f489097ae73a0/ui/display/mojo/display_struct_traits_unittest.cc

So, with the latest changes, what is the best way for the UI to query whether a Display is in tabled mode? Is the intention to use Display::accelerometer_support() == ACCELEROMETER_SUPPORT_AVAILABLE to disable the rotation toggle?

Yes, in your original CL use it instead of is_primary.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/449ec1c2cf54c7664a6ab1ad96ed712057fda281

commit 449ec1c2cf54c7664a6ab1ad96ed712057fda281
Author: Steven Bennetts <stevenjb@chromium.org>
Date: Mon Sep 18 21:01:59 2017

system.display: Provide properties for accelerometer and tablet mode

This CL:
* Adds hasAccelerometerSupport to system.display.DisplayUnitInfo
* Adds isTabletMode to system.display.DisplayUnitInfo (only possible
  if hasAccelerometerSupport is true)
* Updates the Settings UI to disable the orientation control if
  isTabletMode is true

Bug:  704929 
Cq-Include-Trybots: master.tryserver.chromium.linux:closure_compilation
Change-Id: I043a85f6bb886392d5d493d4e519def08f00456c
Reviewed-on: https://chromium-review.googlesource.com/619295
Commit-Queue: Steven Bennetts <stevenjb@chromium.org>
Reviewed-by: Toni Barzic <tbarzic@chromium.org>
Reviewed-by: Devlin <rdevlin.cronin@chromium.org>
Reviewed-by: Mitsuru Oshima <oshima@chromium.org>
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#502673}
[modify] https://crrev.com/449ec1c2cf54c7664a6ab1ad96ed712057fda281/chrome/browser/extensions/display_info_provider_chromeos.cc
[modify] https://crrev.com/449ec1c2cf54c7664a6ab1ad96ed712057fda281/chrome/browser/extensions/display_info_provider_chromeos_unittest.cc
[modify] https://crrev.com/449ec1c2cf54c7664a6ab1ad96ed712057fda281/chrome/browser/resources/settings/device_page/display.html
[modify] https://crrev.com/449ec1c2cf54c7664a6ab1ad96ed712057fda281/extensions/browser/api/system_display/display_info_provider.cc
[modify] https://crrev.com/449ec1c2cf54c7664a6ab1ad96ed712057fda281/extensions/common/api/system_display.idl
[modify] https://crrev.com/449ec1c2cf54c7664a6ab1ad96ed712057fda281/third_party/closure_compiler/externs/system_display.js