Reland "Fix ownership of BluetoothAdapter in BluetoothDeviceChooserController"

This is a reland of 6a9f7032e0150f4202530a38e00262d30b53422d

Original change's description:
> Fix ownership of BluetoothAdapter in BluetoothDeviceChooserController
> 
> BluetoothAdapter is a reference counted object and so
> BluetoothDeviceChooserController should own it using a scoped_refptr.
> Fixing this requires also fixing BluetoothAdapterFactoryWrapper's
> AcquireAdapterCallback to take a scoped_refptr rather than a raw
> pointer. A test for proper ownership has been added.
> 
> (cherry picked from commit a255d1be5723813c1a3e793b8388ed61edcea5b1)
> 
> Bug: 1024121
> Change-Id: I6342322e059f9cbff2a0d5f073f6bccfb0ca7c36
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1914536
> Reviewed-by: Matt Reynolds <mattreynolds@chromium.org>
> Commit-Queue: Reilly Grant <reillyg@chromium.org>
> Cr-Original-Commit-Position: refs/heads/master@{#715206}
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1919803
> Reviewed-by: Krishna Govind <govind@chromium.org>
> Cr-Commit-Position: refs/branch-heads/3904@{#885}
> Cr-Branched-From: 675968a8c657a3bd9c1c2c20c5d2935577bbc5e6-refs/heads/master@{#693954}

Bug: 1024121
Change-Id: I972b5cbcf35f734b103ae4da827a9da7d8aac658
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1920000
Reviewed-by: Reilly Grant <reillyg@chromium.org>
Cr-Commit-Position: refs/branch-heads/3904@{#888}
Cr-Branched-From: 675968a8c657a3bd9c1c2c20c5d2935577bbc5e6-refs/heads/master@{#693954}
7 files changed