The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/aba690d1d703028cb7f77b3ae7b8093c2cb8c087

commit aba690d1d703028cb7f77b3ae7b8093c2cb8c087
Author: mlamouri <mlamouri@chromium.org>
Date: Tue May 09 17:16:40 2017

Media Engagement: implement shell of the media engagement service.

This is created the KeyedService, the WebContentsObserver and the
Feature flag. This is only boilerplate.

BUG= 715051 

Review-Url: https://codereview.chromium.org/2840813002
Cr-Commit-Position: refs/heads/master@{#470362}

[modify] https://crrev.com/aba690d1d703028cb7f77b3ae7b8093c2cb8c087/chrome/browser/BUILD.gn
[modify] https://crrev.com/aba690d1d703028cb7f77b3ae7b8093c2cb8c087/chrome/browser/media/OWNERS
[add] https://crrev.com/aba690d1d703028cb7f77b3ae7b8093c2cb8c087/chrome/browser/media/media_engagement_service.cc
[add] https://crrev.com/aba690d1d703028cb7f77b3ae7b8093c2cb8c087/chrome/browser/media/media_engagement_service.h
[add] https://crrev.com/aba690d1d703028cb7f77b3ae7b8093c2cb8c087/chrome/browser/media/media_engagement_service_factory.cc
[add] https://crrev.com/aba690d1d703028cb7f77b3ae7b8093c2cb8c087/chrome/browser/media/media_engagement_service_factory.h
[modify] https://crrev.com/aba690d1d703028cb7f77b3ae7b8093c2cb8c087/chrome/browser/profiles/chrome_browser_main_extra_parts_profiles.cc
[modify] https://crrev.com/aba690d1d703028cb7f77b3ae7b8093c2cb8c087/chrome/browser/ui/tab_helpers.cc
[modify] https://crrev.com/aba690d1d703028cb7f77b3ae7b8093c2cb8c087/media/base/media_switches.cc
[modify] https://crrev.com/aba690d1d703028cb7f77b3ae7b8093c2cb8c087/media/base/media_switches.h

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/cc3ecbd519b29c785382cfa0f3fcfe27a483aa01

commit cc3ecbd519b29c785382cfa0f3fcfe27a483aa01
Author: Mounir Lamouri <mlamouri@chromium.org>
Date: Wed May 24 09:47:36 2017

Media Engagement: use playback, tab visibility and tab muted as signals.

The implementation does not yet use the following signals:
- audio track;
- muted state;
- video size.

Furthermore, the information are not yet recorded.

Bug:  715051 
Change-Id: I94176ab98b05d5251f0f580c39d064b670e0496d
Reviewed-on: https://chromium-review.googlesource.com/505618
Reviewed-by: Jennifer Apacible <apacible@chromium.org>
Commit-Queue: Mounir Lamouri <mlamouri@chromium.org>
Cr-Commit-Position: refs/heads/master@{#474228}
[modify] https://crrev.com/cc3ecbd519b29c785382cfa0f3fcfe27a483aa01/chrome/browser/BUILD.gn
[add] https://crrev.com/cc3ecbd519b29c785382cfa0f3fcfe27a483aa01/chrome/browser/media/media_engagement_contents_observer.cc
[add] https://crrev.com/cc3ecbd519b29c785382cfa0f3fcfe27a483aa01/chrome/browser/media/media_engagement_contents_observer.h
[add] https://crrev.com/cc3ecbd519b29c785382cfa0f3fcfe27a483aa01/chrome/browser/media/media_engagement_contents_observer_unittest.cc
[modify] https://crrev.com/cc3ecbd519b29c785382cfa0f3fcfe27a483aa01/chrome/browser/media/media_engagement_service.cc
[modify] https://crrev.com/cc3ecbd519b29c785382cfa0f3fcfe27a483aa01/chrome/browser/media/media_engagement_service.h
[modify] https://crrev.com/cc3ecbd519b29c785382cfa0f3fcfe27a483aa01/chrome/test/BUILD.gn

i think this update causes a crash
https://bugs.chromium.org/p/chromium/issues/detail?id=726334

Mounir, can you comment on why you're doing the content observations in the browser process through the WCO? Since media engagement is a service, there doesn't seem to be any reason you couldn't talk to it directly from the renderer - and thus avoid hopping through the WCO interfaces as well as needing to add methods to the WMPDelegate (an interface that should get smaller over time as we wrap up flinging cleanup, not larger).

cc:beccahughes@ since this is salient to a another comment I left about duplication of WT logic for MEI reporting.

On the design, How did you decided on the video size requirement: 200x140?

https://docs.google.com/document/d/1EH7qZatVnTXsBGvQc_53R97Z0xqm6zRblKg3eVmNp30/edit

Calculating the single video size would work for web layouts seen at Netflix, Youtube, Pandora or Amazon Prime (examples shown in the doc), but it wouldn't for websites that shows multiple recorded videos of a conference call for example - such pages are clearly dedicated to and filled with audible media as a main content, but I’m afraid that they will be just restricted since each video size won’t meet the requirement of 200x140. 

As a developer I'd prefer that it calculates the ‘sum’ of the video areas that are seen at the same time without scrolling. 

@ultravisitor - The size is aligned with some our our other video metrics. The way MEI works is that you only need to have a single player greater than 200x140. If you had a conference call wouldn't you normally have a larger video featuring the person who is talking at the moment?

@beccahughes 
Thanks for your reply. Yes, indeed many of the conf-call apps have a large primary video but some are more focused on collaborations, and each video are not necessarily large in this case. (See "Video Conferencing Apps with More Collaboration Features" from below link) 
https://zapier.com/blog/best-video-conferencing-apps/

Assigning this to beccahughes@ as they have implemented most of the feature. Maybe you could link all the bugs you fixed up to this one and close this bug?