To be more specific, the metrics in //chromeos/components/tether/ble_connection_metrics_logger.cc need to be migrated to SecureChannel -- they are no longer logged at all if the multidevice flags are enabled. 

There may also be other metrics we want in addition to these existing ones.

 Issue 857302  has been merged into this issue.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/7bee38bdfa8c38eeadabbe71d2835fb3cb46f77e

commit 7bee38bdfa8c38eeadabbe71d2835fb3cb46f77e
Author: Kyle Horimoto <khorimoto@google.com>
Date: Tue Nov 13 02:59:16 2018

[CrOS MultiDevice] Add metric for BLE connection attempt duration.

This CL adds a metric which measures the time it takes to create a secure
connection to a remote device, from the moment a SecureChannelService client
asks for a new connection (start scanning), to the moment that an authenticated
channel is established with the remote device.

Note that this CL creates latency_metrics_util.h/cc files to fine-tune
the bucket size for this metric. It's created as standalone files because the
same buckets will be used for future metrics.

Bug:  870139 
Change-Id: I62600f9ef0cb1888c9fd4643c89221c5736bfaee
Reviewed-on: https://chromium-review.googlesource.com/c/1327466
Reviewed-by: Steven Holte <holte@chromium.org>
Reviewed-by: James Hawkins <jhawkins@chromium.org>
Commit-Queue: Kyle Horimoto <khorimoto@chromium.org>
Cr-Commit-Position: refs/heads/master@{#607460}
[modify] https://crrev.com/7bee38bdfa8c38eeadabbe71d2835fb3cb46f77e/chromeos/services/secure_channel/BUILD.gn
[modify] https://crrev.com/7bee38bdfa8c38eeadabbe71d2835fb3cb46f77e/chromeos/services/secure_channel/ble_listener_connection_attempt.cc
[modify] https://crrev.com/7bee38bdfa8c38eeadabbe71d2835fb3cb46f77e/chromeos/services/secure_channel/ble_listener_connection_attempt.h
[modify] https://crrev.com/7bee38bdfa8c38eeadabbe71d2835fb3cb46f77e/chromeos/services/secure_channel/connection_attempt.h
[modify] https://crrev.com/7bee38bdfa8c38eeadabbe71d2835fb3cb46f77e/chromeos/services/secure_channel/connection_attempt_base.h
[modify] https://crrev.com/7bee38bdfa8c38eeadabbe71d2835fb3cb46f77e/chromeos/services/secure_channel/fake_connection_attempt.h
[add] https://crrev.com/7bee38bdfa8c38eeadabbe71d2835fb3cb46f77e/chromeos/services/secure_channel/latency_metrics_logger.cc
[add] https://crrev.com/7bee38bdfa8c38eeadabbe71d2835fb3cb46f77e/chromeos/services/secure_channel/latency_metrics_logger.h
[modify] https://crrev.com/7bee38bdfa8c38eeadabbe71d2835fb3cb46f77e/tools/metrics/histograms/histograms.xml

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/893d53cefc161573f57ba2d92bab544a38fed66d

commit 893d53cefc161573f57ba2d92bab544a38fed66d
Author: Kyle Horimoto <khorimoto@chromium.org>
Date: Tue Nov 20 19:37:31 2018

[CrOS MultiDevice] Add latency metrics for BLE connections.

This CL adds latency metrics for sub-tasks of BLE connections:
  * start scan ==> receive advertisement
  * start scan ==> GATT connection
  * receive advertisement ==> GATT connection
  * GATT connection ==> authentication

Bug:  870139 
Change-Id: If1f4230bb873e097a10963f8fc86003afc1146ac
Reviewed-on: https://chromium-review.googlesource.com/c/1336921
Reviewed-by: Robert Kaplow <rkaplow@chromium.org>
Reviewed-by: Ryan Hansberry <hansberry@chromium.org>
Commit-Queue: Kyle Horimoto <khorimoto@chromium.org>
Cr-Commit-Position: refs/heads/master@{#609775}
[modify] https://crrev.com/893d53cefc161573f57ba2d92bab544a38fed66d/chromeos/services/secure_channel/ble_connection_manager_impl.cc
[modify] https://crrev.com/893d53cefc161573f57ba2d92bab544a38fed66d/chromeos/services/secure_channel/ble_connection_manager_impl.h
[modify] https://crrev.com/893d53cefc161573f57ba2d92bab544a38fed66d/chromeos/services/secure_channel/ble_connection_manager_impl_unittest.cc
[modify] https://crrev.com/893d53cefc161573f57ba2d92bab544a38fed66d/chromeos/services/secure_channel/secure_channel_service_unittest.cc
[modify] https://crrev.com/893d53cefc161573f57ba2d92bab544a38fed66d/tools/metrics/histograms/histograms.xml

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/f3b934ae55ef79c5b81041d4b76ddb161da1d1f9

commit f3b934ae55ef79c5b81041d4b76ddb161da1d1f9
Author: Kyle Horimoto <khorimoto@chromium.org>
Date: Tue Nov 27 22:02:27 2018

[CrOS MultiDevice] Add SecureChannel stability metrics.

These metrics all measure the "effective success rate" of various
sub-tasks of creating a connection. In this context, the effective rate
includes retries, meaning that a failure followed by a successful retry
is counted as one "success" metric.

Metrics added in this CL:
  * Start scan ==> GATT connection
  * Start scan ==> Authentication
  * GATT connection ==> Authentication

Bug:  870139 
Change-Id: Ic8796cf7501d9a1ecf3fb08ec788e1f0a487488e
Reviewed-on: https://chromium-review.googlesource.com/c/1344999
Commit-Queue: Kyle Horimoto <khorimoto@chromium.org>
Reviewed-by: Ilya Sherman <isherman@chromium.org>
Reviewed-by: Ryan Hansberry <hansberry@chromium.org>
Cr-Commit-Position: refs/heads/master@{#611356}
[modify] https://crrev.com/f3b934ae55ef79c5b81041d4b76ddb161da1d1f9/chromeos/services/secure_channel/ble_connection_manager_impl.cc
[modify] https://crrev.com/f3b934ae55ef79c5b81041d4b76ddb161da1d1f9/chromeos/services/secure_channel/ble_connection_manager_impl.h
[modify] https://crrev.com/f3b934ae55ef79c5b81041d4b76ddb161da1d1f9/chromeos/services/secure_channel/ble_connection_manager_impl_unittest.cc
[modify] https://crrev.com/f3b934ae55ef79c5b81041d4b76ddb161da1d1f9/tools/metrics/histograms/histograms.xml