The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/1a4bf05557f2f9049b344df0669ad2f4f3072be6

commit 1a4bf05557f2f9049b344df0669ad2f4f3072be6
Author: Marina Ciocea <marinaciocea@chromium.org>
Date: Wed May 23 14:24:39 2018

Add audio manager startup time UMA metric.

Add metric to monitor how long it takes for the audio manager instance to be created by
the audio service. This startup time contributes to the first request served by the audio service.

Audio service design doc: https://docs.google.com/document/d/1s_Fd1WRDdpb5n6C2MSJjeC3fis6hULZwfKMeDd4K5tI/edit?usp=sharing

Bug:  845813 
Change-Id: I21a2983558aff1362051676afb39f280da113175
Reviewed-on: https://chromium-review.googlesource.com/1068676
Reviewed-by: Gayane Petrosyan <gayane@chromium.org>
Reviewed-by: Olga Sharonova <olka@chromium.org>
Commit-Queue: Marina Ciocea <marinaciocea@chromium.org>
Cr-Commit-Position: refs/heads/master@{#561068}
[modify] https://crrev.com/1a4bf05557f2f9049b344df0669ad2f4f3072be6/services/audio/owning_audio_manager_accessor.cc
[modify] https://crrev.com/1a4bf05557f2f9049b344df0669ad2f4f3072be6/tools/metrics/histograms/histograms.xml

[bulk-edit: disregard if N/A] Can the owner please set milestone to this bug if applicable?