We should also not construct any of the BLE-related classes at all. It would have been really bad had we not caught this issue, since ConnectionPreserver would start trying to make a connection via BleConnectionManager, and this connection would interfere with the one which is created via SecureChannelClient.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/d483a82751d7df6313b4ef007c9f04db49ca4614

commit d483a82751d7df6313b4ef007c9f04db49ca4614
Author: Ryan Hansberry <hansberry@chromium.org>
Date: Thu Jun 28 00:32:05 2018

[CrOS Multidevice] Integrate SecureChannel API with ConnectionPreserver.

Uses SecureChannelClient to keep a connection open with the appropriate
remote device. This change also requires slightly tweaking HostScannerOperation
to delay unregistering the remote device in question until ConnectionPreserver
has fully had a chance to communicate with the Mojo SecureChannel service.

Bug: 824568,  752273 ,  855813 
Change-Id: I6c8c915ab1efbae9c77e08c9c9b2406a5b4de2ad
Reviewed-on: https://chromium-review.googlesource.com/1117558
Commit-Queue: Ryan Hansberry <hansberry@chromium.org>
Reviewed-by: Kyle Horimoto <khorimoto@chromium.org>
Cr-Commit-Position: refs/heads/master@{#570979}
[modify] https://crrev.com/d483a82751d7df6313b4ef007c9f04db49ca4614/chromeos/components/tether/connection_preserver_impl.cc
[modify] https://crrev.com/d483a82751d7df6313b4ef007c9f04db49ca4614/chromeos/components/tether/connection_preserver_impl.h
[modify] https://crrev.com/d483a82751d7df6313b4ef007c9f04db49ca4614/chromeos/components/tether/connection_preserver_impl_unittest.cc
[modify] https://crrev.com/d483a82751d7df6313b4ef007c9f04db49ca4614/chromeos/components/tether/host_scanner_operation.cc
[modify] https://crrev.com/d483a82751d7df6313b4ef007c9f04db49ca4614/chromeos/components/tether/host_scanner_operation.h
[modify] https://crrev.com/d483a82751d7df6313b4ef007c9f04db49ca4614/chromeos/components/tether/host_scanner_operation_unittest.cc
[modify] https://crrev.com/d483a82751d7df6313b4ef007c9f04db49ca4614/chromeos/components/tether/synchronous_shutdown_object_container_impl.cc
[modify] https://crrev.com/d483a82751d7df6313b4ef007c9f04db49ca4614/chromeos/services/secure_channel/public/cpp/client/fake_client_channel.cc
[modify] https://crrev.com/d483a82751d7df6313b4ef007c9f04db49ca4614/chromeos/services/secure_channel/public/cpp/client/fake_client_channel.h
[modify] https://crrev.com/d483a82751d7df6313b4ef007c9f04db49ca4614/chromeos/services/secure_channel/public/cpp/client/fake_secure_channel_client.h

Ryan, you either need to re-open this bug to address my comment #1 or file a new bug for that comment. It's important that we eliminate any possibility of the BLE code being invoked when the flag is on.

comment #4 was addressed in https://chromium-review.googlesource.com/c/chromium/src/+/1117897, meaning this issue is now fully resolved.