Thanks for the bug. TrayBluetoothHelperLegacy shouldn't be notifying of state changed if there is no actual state changed. I'll fix TrayBluetoothHelperLegacy and then try to reland the original patch.

Also downgrading to P2 since the patch got reverted.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/70b34093945291add162c9b21c509d6f43a560b3

commit 70b34093945291add162c9b21c509d6f43a560b3
Author: Giovanni Ortuño Urquidi <ortuno@chromium.org>
Date: Wed Nov 28 22:49:53 2018

bluetooth: Don't call OnBluetoothStateChanged if the state doesn't change

AdapterPoweredChanged gets called right after AdapterPresentChanged when
an adapter is added or removed. This causes us to call
Observer::OnBluetoothStateChanged() a second time without the state
actually changing. To avoid this, we cache the state whenever
AdapterPresentChanged and AdapterPoweredChanged get called and only notify
if the new state is different than the cached state.

Bug:  908879 
Change-Id: I7ca48b20678b5336346955fd2254bc68f2a09b75
Reviewed-on: https://chromium-review.googlesource.com/c/1352123
Commit-Queue: Giovanni Ortuño Urquidi <ortuno@chromium.org>
Reviewed-by: Tetsui Ohkubo <tetsui@chromium.org>
Cr-Commit-Position: refs/heads/master@{#611911}
[modify] https://crrev.com/70b34093945291add162c9b21c509d6f43a560b3/ash/system/bluetooth/tray_bluetooth_helper.h
[modify] https://crrev.com/70b34093945291add162c9b21c509d6f43a560b3/ash/system/bluetooth/tray_bluetooth_helper_legacy.cc
[modify] https://crrev.com/70b34093945291add162c9b21c509d6f43a560b3/ash/system/bluetooth/tray_bluetooth_helper_legacy.h
[modify] https://crrev.com/70b34093945291add162c9b21c509d6f43a560b3/ash/system/bluetooth/tray_bluetooth_helper_legacy_unittest.cc