The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/bf7e4982490455401d17fee6ef4d9083a3f120bf

commit bf7e4982490455401d17fee6ef4d9083a3f120bf
Author: Raymond Toy <rtoy@chromium.org>
Date: Thu Jul 19 00:09:53 2018

Detect if output is audible or not

Measure the output of the destination to determine if the output
is audible or not.  Also keep track of the total duration of when
audible output was played.

Bug:  855069 
Change-Id: Icec9aa3d3b853bb5b4b9287ce9350d2e16cd383e
Reviewed-on: https://chromium-review.googlesource.com/1102664
Commit-Queue: Raymond Toy <rtoy@chromium.org>
Reviewed-by: Mounir Lamouri <mlamouri@chromium.org>
Reviewed-by: Hongchan Choi <hongchan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#576268}
[modify] https://crrev.com/bf7e4982490455401d17fee6ef4d9083a3f120bf/third_party/blink/renderer/platform/audio/audio_destination.cc
[modify] https://crrev.com/bf7e4982490455401d17fee6ef4d9083a3f120bf/third_party/blink/renderer/platform/audio/audio_destination.h

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/83fec715c8abfa2a74768bc37b245728e60a899e

commit 83fec715c8abfa2a74768bc37b245728e60a899e
Author: Raymond Toy <rtoy@chromium.org>
Date: Fri Aug 10 02:53:40 2018

Move audibility detection to BaseAudioContext

Have the BaseAudioContext do the audibility detection instead of the
AudioDestination.  And also post a task to the main thread when
audible audio starts or stops.  This is in preparation for reporting
this information to the browser.

Bug:  855069 
Test: 
Change-Id: I8abd9be664697e8cc02998daec06f9ca0d34a98d
Reviewed-on: https://chromium-review.googlesource.com/1165947
Reviewed-by: Hongchan Choi <hongchan@chromium.org>
Commit-Queue: Raymond Toy <rtoy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#582029}
[modify] https://crrev.com/83fec715c8abfa2a74768bc37b245728e60a899e/third_party/blink/renderer/modules/webaudio/base_audio_context.cc
[modify] https://crrev.com/83fec715c8abfa2a74768bc37b245728e60a899e/third_party/blink/renderer/modules/webaudio/base_audio_context.h
[modify] https://crrev.com/83fec715c8abfa2a74768bc37b245728e60a899e/third_party/blink/renderer/modules/webaudio/default_audio_destination_node.cc
[modify] https://crrev.com/83fec715c8abfa2a74768bc37b245728e60a899e/third_party/blink/renderer/platform/audio/audio_destination.cc
[modify] https://crrev.com/83fec715c8abfa2a74768bc37b245728e60a899e/third_party/blink/renderer/platform/audio/audio_destination.h

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/e413650c2e245c5e87b87bde97f15ab9f280ec9e

commit e413650c2e245c5e87b87bde97f15ab9f280ec9e
Author: Raymond Toy <rtoy@chromium.org>
Date: Fri Aug 31 00:12:47 2018

Record whether AudioContext was audible for Autoplay UKM

Implements AudioContextManager mojo interface that can be obtained from a frame so that
audible playback from WebAudio can be recorded by the browser.  Whenever audible playback
starts or stops, a message is sent to the browser indicating such.

Bug:  855069 
Change-Id: Ib236a9506a2a6d9b53e95948eb5519145805a2cb
Reviewed-on: https://chromium-review.googlesource.com/1114147
Reviewed-by: Mounir Lamouri <mlamouri@chromium.org>
Reviewed-by: Ken Buchanan <kenrb@chromium.org>
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Reviewed-by: Kinuko Yasuda <kinuko@chromium.org>
Reviewed-by: Nasko Oskov <nasko@chromium.org>
Reviewed-by: Hongchan Choi <hongchan@chromium.org>
Commit-Queue: Raymond Toy <rtoy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#587867}
[modify] https://crrev.com/e413650c2e245c5e87b87bde97f15ab9f280ec9e/content/browser/BUILD.gn
[modify] https://crrev.com/e413650c2e245c5e87b87bde97f15ab9f280ec9e/content/browser/frame_host/interstitial_page_impl.cc
[modify] https://crrev.com/e413650c2e245c5e87b87bde97f15ab9f280ec9e/content/browser/frame_host/interstitial_page_impl.h
[modify] https://crrev.com/e413650c2e245c5e87b87bde97f15ab9f280ec9e/content/browser/frame_host/render_frame_host_delegate.h
[modify] https://crrev.com/e413650c2e245c5e87b87bde97f15ab9f280ec9e/content/browser/frame_host/render_frame_host_impl.cc
[modify] https://crrev.com/e413650c2e245c5e87b87bde97f15ab9f280ec9e/content/browser/frame_host/render_frame_host_impl.h
[add] https://crrev.com/e413650c2e245c5e87b87bde97f15ab9f280ec9e/content/browser/media/webaudio/audio_context_manager_browsertest.cc
[add] https://crrev.com/e413650c2e245c5e87b87bde97f15ab9f280ec9e/content/browser/media/webaudio/audio_context_manager_impl.cc
[add] https://crrev.com/e413650c2e245c5e87b87bde97f15ab9f280ec9e/content/browser/media/webaudio/audio_context_manager_impl.h
[modify] https://crrev.com/e413650c2e245c5e87b87bde97f15ab9f280ec9e/content/browser/web_contents/web_contents_impl.cc
[modify] https://crrev.com/e413650c2e245c5e87b87bde97f15ab9f280ec9e/content/browser/web_contents/web_contents_impl.h
[modify] https://crrev.com/e413650c2e245c5e87b87bde97f15ab9f280ec9e/content/public/app/mojo/content_browser_manifest.json
[modify] https://crrev.com/e413650c2e245c5e87b87bde97f15ab9f280ec9e/content/public/browser/web_contents_observer.h
[modify] https://crrev.com/e413650c2e245c5e87b87bde97f15ab9f280ec9e/content/test/BUILD.gn
[add] https://crrev.com/e413650c2e245c5e87b87bde97f15ab9f280ec9e/content/test/data/media/webaudio/playback-test.html
[modify] https://crrev.com/e413650c2e245c5e87b87bde97f15ab9f280ec9e/third_party/blink/public/mojom/BUILD.gn
[add] https://crrev.com/e413650c2e245c5e87b87bde97f15ab9f280ec9e/third_party/blink/public/mojom/webaudio/OWNERS
[add] https://crrev.com/e413650c2e245c5e87b87bde97f15ab9f280ec9e/third_party/blink/public/mojom/webaudio/audio_context_manager.mojom
[modify] https://crrev.com/e413650c2e245c5e87b87bde97f15ab9f280ec9e/third_party/blink/renderer/modules/webaudio/audio_context.cc
[modify] https://crrev.com/e413650c2e245c5e87b87bde97f15ab9f280ec9e/third_party/blink/renderer/modules/webaudio/audio_context.h
[modify] https://crrev.com/e413650c2e245c5e87b87bde97f15ab9f280ec9e/third_party/blink/renderer/modules/webaudio/base_audio_context.cc
[modify] https://crrev.com/e413650c2e245c5e87b87bde97f15ab9f280ec9e/third_party/blink/renderer/modules/webaudio/base_audio_context.h

It looks like the CL did not make the branch cut for 70.

Your change meets the bar and is auto-approved for M70. Please go ahead and merge the CL to branch 3538 manually. Please contact milestone owner if you have questions.
Owners: benmason@(Android), kariahda@(iOS), geohsu@(ChromeOS), abdulsyed@(Desktop)

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot

https://chromium-review.googlesource.com/c/chromium/src/+/1207810 has the merge to M70 (3538), but this bug hasn't been updated yet.  I'm going to wait a little more to see if it updates this.

Thanks, beccahughes@, for requesting the merge request for me.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/833b84f4ac4e5a794b88ce0638c2a2bdac08fce5

commit 833b84f4ac4e5a794b88ce0638c2a2bdac08fce5
Author: Raymond Toy <rtoy@chromium.org>
Date: Wed Sep 05 17:57:03 2018

Record whether AudioContext was audible for Autoplay UKM

Implements AudioContextManager mojo interface that can be obtained from a frame so that
audible playback from WebAudio can be recorded by the browser.  Whenever audible playback
starts or stops, a message is sent to the browser indicating such.

Bug:  855069 
Change-Id: Ib236a9506a2a6d9b53e95948eb5519145805a2cb
Reviewed-on: https://chromium-review.googlesource.com/1114147
Reviewed-by: Mounir Lamouri <mlamouri@chromium.org>
Reviewed-by: Ken Buchanan <kenrb@chromium.org>
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Reviewed-by: Kinuko Yasuda <kinuko@chromium.org>
Reviewed-by: Nasko Oskov <nasko@chromium.org>
Reviewed-by: Hongchan Choi <hongchan@chromium.org>
Commit-Queue: Raymond Toy <rtoy@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#587867}(cherry picked from commit e413650c2e245c5e87b87bde97f15ab9f280ec9e)
Reviewed-on: https://chromium-review.googlesource.com/1207810
Reviewed-by: Raymond Toy <rtoy@chromium.org>
Cr-Commit-Position: refs/branch-heads/3538@{#55}
Cr-Branched-From: 79f7c91a2b2a2932cd447fa6f865cb6662fa8fa6-refs/heads/master@{#587811}
[modify] https://crrev.com/833b84f4ac4e5a794b88ce0638c2a2bdac08fce5/content/browser/BUILD.gn
[modify] https://crrev.com/833b84f4ac4e5a794b88ce0638c2a2bdac08fce5/content/browser/frame_host/interstitial_page_impl.cc
[modify] https://crrev.com/833b84f4ac4e5a794b88ce0638c2a2bdac08fce5/content/browser/frame_host/interstitial_page_impl.h
[modify] https://crrev.com/833b84f4ac4e5a794b88ce0638c2a2bdac08fce5/content/browser/frame_host/render_frame_host_delegate.h
[modify] https://crrev.com/833b84f4ac4e5a794b88ce0638c2a2bdac08fce5/content/browser/frame_host/render_frame_host_impl.cc
[modify] https://crrev.com/833b84f4ac4e5a794b88ce0638c2a2bdac08fce5/content/browser/frame_host/render_frame_host_impl.h
[add] https://crrev.com/833b84f4ac4e5a794b88ce0638c2a2bdac08fce5/content/browser/media/webaudio/audio_context_manager_browsertest.cc
[add] https://crrev.com/833b84f4ac4e5a794b88ce0638c2a2bdac08fce5/content/browser/media/webaudio/audio_context_manager_impl.cc
[add] https://crrev.com/833b84f4ac4e5a794b88ce0638c2a2bdac08fce5/content/browser/media/webaudio/audio_context_manager_impl.h
[modify] https://crrev.com/833b84f4ac4e5a794b88ce0638c2a2bdac08fce5/content/browser/web_contents/web_contents_impl.cc
[modify] https://crrev.com/833b84f4ac4e5a794b88ce0638c2a2bdac08fce5/content/browser/web_contents/web_contents_impl.h
[modify] https://crrev.com/833b84f4ac4e5a794b88ce0638c2a2bdac08fce5/content/public/app/mojo/content_browser_manifest.json
[modify] https://crrev.com/833b84f4ac4e5a794b88ce0638c2a2bdac08fce5/content/public/browser/web_contents_observer.h
[modify] https://crrev.com/833b84f4ac4e5a794b88ce0638c2a2bdac08fce5/content/test/BUILD.gn
[add] https://crrev.com/833b84f4ac4e5a794b88ce0638c2a2bdac08fce5/content/test/data/media/webaudio/playback-test.html
[modify] https://crrev.com/833b84f4ac4e5a794b88ce0638c2a2bdac08fce5/third_party/blink/public/mojom/BUILD.gn
[add] https://crrev.com/833b84f4ac4e5a794b88ce0638c2a2bdac08fce5/third_party/blink/public/mojom/webaudio/OWNERS
[add] https://crrev.com/833b84f4ac4e5a794b88ce0638c2a2bdac08fce5/third_party/blink/public/mojom/webaudio/audio_context_manager.mojom
[modify] https://crrev.com/833b84f4ac4e5a794b88ce0638c2a2bdac08fce5/third_party/blink/renderer/modules/webaudio/audio_context.cc
[modify] https://crrev.com/833b84f4ac4e5a794b88ce0638c2a2bdac08fce5/third_party/blink/renderer/modules/webaudio/audio_context.h
[modify] https://crrev.com/833b84f4ac4e5a794b88ce0638c2a2bdac08fce5/third_party/blink/renderer/modules/webaudio/base_audio_context.cc
[modify] https://crrev.com/833b84f4ac4e5a794b88ce0638c2a2bdac08fce5/third_party/blink/renderer/modules/webaudio/base_audio_context.h

I think we can close this now; we've implemented the ukm events.