rkc@, scheib@ - Is there a way to tell whether or not scanning is in progress? Do we log that anywhere?

After step 4 in #0 , we can see that the Bluetooth scanning is still on in the bt_console page in shell. 

But i don't see any audio sluttering.

#2, interesting, maybe you can comment on bug 700959, I could see it on 2 different samus devices although I've only tried one set of headphones (I've mentioned the exact setup on that other bug).

MD settings is only a Finch experiment in M58

This can also be detected by observing chrome://bluetooth-internals/#adapter

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.

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