My guess is this is caused by there being some delay between disabling mobile data and it actually being disabled (similar to Bluetooth). If you try to re-enable in the UI before it is actually disabled, it then completes disabling and turns back off.

Small chance that it's a new issue introduced by MD Settings since we're seeing reports on both of these UIs?

I do seem to recall there being some debouncing in the old UI to avoid this, although I won't swear to it.

I don't see a video to refer to, but we should disable the button (logically if not visibly) while the Cellular (or WiFi or WiMAX) technology state is 'TECHNOLOGY_ENABLING'.

I'm less familiar with the bluetooth states, but I would expect it to have a similar need.

I am unaware of anything that might have changed in the network configuration or Shill code to cause this.

->tdanderson@ for StatusArea triage.

Valery, mind taking a first look? Tentatively targeting this for m-57.

Capturing some notes from a chat with Valery. We could address this by:

* When clicking the toggle button, show immediate UI feedback from user's point of view (toggle button thumb moves). Set a timer for, say, 4 seconds.

* Behind the scenes track the on/off state of the toggle. Note this state can be mutated by other things (e.g., removing a SIM card, change in mobile network, etc).

* After the 4 second timer expires, check the current on/off state. If it is inconsistent with the current appearance of the toggle button then update the toggle button. Otherwise do nothing.

Note this can and should be generalized for all toggle buttons (WiFi, Bluetooth) as they can potentially suffer from the same problem.

Part of the UI feedback should be disabling the toggle for the duration of the timer, correct?

#5 probably won't work - the I don't think the states can be queued to enable this. I think just disabling the toggle when it is pressed and re-enabling when the state is updated will do the trick.
Tested the Bluetooth on device and I don't think it suffers from the same problem so I will leave it alone.

Draft at https://codereview.chromium.org/2702493002.

Are you saying that you can't repro the Bluetooth issue, or that it has a different cause?

I can still repro Bluetooth on 57.0.2987.32 dev -- toggle it off & on quickly, then it is atuo-disabled a couple seconds later.

I couldn't on link (ToT) but I can with samus (Dev). I think a similar fix as described in #5 could work. Will try that. 

Thanks Valery!

Issue 671410 has been merged into this issue.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/6a8e668da879ad1fc3b442a8c9a2be69b1a9a692

commit 6a8e668da879ad1fc3b442a8c9a2be69b1a9a692
Author: varkha <varkha@chromium.org>
Date: Wed Mar 08 02:41:00 2017

[ash-md] Disables the Wi-Fi and Cellular toggles until the state changes

BUG= 687922 
TEST=Visual
     On a mobile-equipped Chromebook (e.g. link with 3G)
     Try to toggle Mobile toggle off and immediately on
     Expected: The toggle cannot be re-enabled immediately.
     When it can finally be re-enabled, it stays enabled.

Review-Url: https://codereview.chromium.org/2702493002
Cr-Commit-Position: refs/heads/master@{#455357}

[modify] https://crrev.com/6a8e668da879ad1fc3b442a8c9a2be69b1a9a692/ash/common/system/chromeos/bluetooth/tray_bluetooth.cc
[modify] https://crrev.com/6a8e668da879ad1fc3b442a8c9a2be69b1a9a692/ash/common/system/chromeos/network/network_list_md.cc

Tested on device with mobile radio. I'm not really sure if this is in fact a blocker due to low number of mobile radio equipped devices, however requesting a merge.

Your change meets the bar and is auto-approved for M58. Please go ahead and merge the CL to branch 3029 manually. Please contact milestone owner if you have questions.
Owners: amineer@(clank), cmasso@(bling), bhthompson@(cros), govind@(desktop)

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/83c7f2bc6aa21a29fbf37ec1eda83dfac1570cfe

commit 83c7f2bc6aa21a29fbf37ec1eda83dfac1570cfe
Author: Valery Arkhangorodsky <varkha@chromium.org>
Date: Thu Mar 09 21:44:19 2017

[ash-md] Disables the Wi-Fi and Cellular toggles until the state changes

BUG= 687922 
TEST=Visual
     On a mobile-equipped Chromebook (e.g. link with 3G)
     Try to toggle Mobile toggle off and immediately on
     Expected: The toggle cannot be re-enabled immediately.
     When it can finally be re-enabled, it stays enabled.

Review-Url: https://codereview.chromium.org/2702493002
Cr-Commit-Position: refs/heads/master@{#455357}
(cherry picked from commit 6a8e668da879ad1fc3b442a8c9a2be69b1a9a692)

Review-Url: https://codereview.chromium.org/2743783002 .
Cr-Commit-Position: refs/branch-heads/3029@{#92}
Cr-Branched-From: 939b32ee5ba05c396eef3fd992822fcca9a2e262-refs/heads/master@{#454471}

[modify] https://crrev.com/83c7f2bc6aa21a29fbf37ec1eda83dfac1570cfe/ash/common/system/chromeos/bluetooth/tray_bluetooth.cc
[modify] https://crrev.com/83c7f2bc6aa21a29fbf37ec1eda83dfac1570cfe/ash/common/system/chromeos/network/network_list_md.cc

Verified on 58/9334.33.0/58.0.3029.51