Hmm, this is surprising and I can't reproduce without a connected device, can someone verify this?

Also, could you clarify 'play media' in case that is a factor (and confirm the repeatability of this? Does it occur if settings is already open or was already open?)

#1, on my samus I can reproduce this by those steps (no device involved although I have phone shown there as a paired device and I have smart lock enabled.
+ Tap system tray, verify BT is enabled.
+ Open a new window, type chrome://md-settings in URL
Bluetooth toggle momentarily shows on but immediately gets turned off.
Verifying in system tray - BT is now turned off.

I can not reproduce #2 on a ToT build. I will try on a 58 build some time this week.

Verified with comment #2 on samus on 58.0.3029.40. Doesn't require any paired device.

Does not repro on old Options. Repros consistently in MD Settings.

also on 58.0.3029.51.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/f4de1dce7be5bc5c6fcf4615478757773dace027

commit f4de1dce7be5bc5c6fcf4615478757773dace027
Author: stevenjb <stevenjb@chromium.org>
Date: Thu Apr 13 02:47:46 2017

MD Settings: Bluetooth: Fix adapter state and discovery

This CL:
* Adds some additional bluetooth event logging (USER events).
* Fixes the toggle logic so as not to set powered=false before the
  adapter state is received or when the toggle state matches the
  adapter state.
* Disables the toggle until the adapter state changes (not normally
  observable, but can prevent rapid toggling artifacts).
* Modifies BluetoothEventRouter to stop discovery when all WebUI tabs
  (or all tabs/windows associated with an extension) are closed.

BUG= 703694 , 703698 
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:closure_compilation

Review-Url: https://codereview.chromium.org/2801403002
Cr-Commit-Position: refs/heads/master@{#464258}

[modify] https://crrev.com/f4de1dce7be5bc5c6fcf4615478757773dace027/chrome/browser/resources/settings/bluetooth_page/bluetooth_page.html
[modify] https://crrev.com/f4de1dce7be5bc5c6fcf4615478757773dace027/chrome/browser/resources/settings/bluetooth_page/bluetooth_page.js
[modify] https://crrev.com/f4de1dce7be5bc5c6fcf4615478757773dace027/chrome/browser/resources/settings/bluetooth_page/bluetooth_subpage.html
[modify] https://crrev.com/f4de1dce7be5bc5c6fcf4615478757773dace027/chrome/browser/resources/settings/bluetooth_page/bluetooth_subpage.js
[modify] https://crrev.com/f4de1dce7be5bc5c6fcf4615478757773dace027/chrome/test/data/webui/settings/bluetooth_page_tests.js
[modify] https://crrev.com/f4de1dce7be5bc5c6fcf4615478757773dace027/chrome/test/data/webui/settings/fake_bluetooth.js
[modify] https://crrev.com/f4de1dce7be5bc5c6fcf4615478757773dace027/chrome/test/data/webui/settings/fake_bluetooth_private.js
[modify] https://crrev.com/f4de1dce7be5bc5c6fcf4615478757773dace027/extensions/browser/api/DEPS
[modify] https://crrev.com/f4de1dce7be5bc5c6fcf4615478757773dace027/extensions/browser/api/bluetooth/bluetooth_api.cc
[modify] https://crrev.com/f4de1dce7be5bc5c6fcf4615478757773dace027/extensions/browser/api/bluetooth/bluetooth_event_router.cc
[modify] https://crrev.com/f4de1dce7be5bc5c6fcf4615478757773dace027/extensions/browser/api/bluetooth/bluetooth_event_router.h
[modify] https://crrev.com/f4de1dce7be5bc5c6fcf4615478757773dace027/extensions/browser/api/bluetooth/bluetooth_event_router_unittest.cc
[modify] https://crrev.com/f4de1dce7be5bc5c6fcf4615478757773dace027/extensions/browser/api/bluetooth/bluetooth_private_api.cc

[Auto-generated comment by a script] We noticed that this issue is targeted for M-59; it appears the fix may have landed after branch point, meaning a merge might be required. Please confirm if a merge is required here - if so add Merge-Request-59 label, otherwise remove Merge-TBD label. Thanks.

Issue still observed on ChromeOS-test-R60-9469.0.0. Kindly let me know when this is going to get merged 

Crhome is still at 59.0.3070.0 in that version, which corresponds to commit #464226.

The fix landed at #464258.

It should be in the next *Chrome* update, which is behind a bit due to a series of cascading failures in the PFQ.

This is now fixes in 59.0.3071.15 / 9460.5.0 build