haraken@, is it OK to reland that patch (updating LeakExpectations) and fix the leak later?

Also, is there a way to see what are the leaking ActiveDOMObjects? If there are some verbose logging, it would help a lot debugging the issue.

I think we should revert the CL and reland with the fix.

> is there a way to see what are the leaking ActiveDOMObjects?

There's no easy way, unfortunately :/ However, I guess the leaking ActiveDOMObject is HTMLMediaElement.

> There's no easy way, unfortunately :/ However, I guess the leaking ActiveDOMObject is HTMLMediaElement.

I think so, too. But the info is not enough to debug the leak.

I suspect the leak is because that some persistent reference in the graph is preventing the HTMLMediaElement to be GC'ed, event if the document is unloaded. Does this sound reasonable? Is there other possible reasons?

Did some more logging. Seems like we can exclude the following classes:
- Document
- HTMLMediaElement
- ElementVisibilityObserver
- IntersectionObserver
- IntersectionObservation
- IntersectionObservationController

Looking into more.

[1:1:0831/174904:112999682081:INFO:Document.cpp(458)] Document::Document()
[1:1:0831/174904:112999682425:INFO:ActiveDOMObject.cpp(40)] ActiveDOMObject::ActiveDOMObject()
[1:1:0831/174904:112999682561:INFO:ActiveDOMObject.cpp(40)] ActiveDOMObject::ActiveDOMObject()
[1:1:0831/174904:112999701153:INFO:Document.cpp(458)] Document::Document()
[1:1:0831/174904:112999701278:INFO:ActiveDOMObject.cpp(40)] ActiveDOMObject::ActiveDOMObject()
[1:1:0831/174904:112999701351:INFO:ActiveDOMObject.cpp(40)] ActiveDOMObject::ActiveDOMObject()
[1:1:0831/174904:112999719550:INFO:ActiveDOMObject.cpp(40)] ActiveDOMObject::ActiveDOMObject()
[1:1:0831/174904:112999721507:INFO:ActiveDOMObject.cpp(40)] ActiveDOMObject::ActiveDOMObject()
[1:1:0831/174904:112999728844:INFO:ActiveDOMObject.cpp(40)] ActiveDOMObject::ActiveDOMObject()
[1:1:0831/174904:112999728943:INFO:AutoplayUmaHelper.cpp(40)] AutoplayUmaHelper::AutoplayUmaHelper()
[1:1:0831/174904:112999728996:INFO:HTMLMediaElement.cpp(448)] HTMLMediaElement::HTMLMediaElement()
[1:1:0831/174904:112999729538:INFO:ActiveDOMObject.cpp(40)] ActiveDOMObject::ActiveDOMObject()
[1:1:0831/174904:112999729619:INFO:AutoplayUmaHelper.cpp(40)] AutoplayUmaHelper::AutoplayUmaHelper()
[1:1:0831/174904:112999729670:INFO:HTMLMediaElement.cpp(448)] HTMLMediaElement::HTMLMediaElement()
[57943:57964:0831/174904:113000094278:INFO:audio_manager_pulse.cc(204)] Not implemented!
[57943:57964:0831/174904:113000096964:INFO:audio_manager_pulse.cc(204)] Not implemented!
[1:1:0831/174904:113000102571:INFO:ElementVisibilityObserver.cpp(28)] ElementVisibilityObserver::ElementVisibilityObserver()
[1:1:0831/174904:113000102737:INFO:IntersectionObserver.cpp(188)] IntersectionObserver::IntersectionObserver()
[1:1:0831/174904:113000102816:INFO:ActiveDOMObject.cpp(40)] ActiveDOMObject::ActiveDOMObject()
[1:1:0831/174904:113000102878:INFO:IntersectionObserverController.cpp(25)] IntersectionObserverController::IntersectionObserverController()
[1:1:0831/174904:113000102954:INFO:IntersectionObservation.cpp(23)] IntersectionObservation::IntersectionObservation()
[1:1:0831/174904:113000105443:INFO:ActiveDOMObject.cpp(40)] ActiveDOMObject::ActiveDOMObject()
[1:1:0831/174904:113000212944:INFO:ActiveDOMObject.cpp(40)] ActiveDOMObject::ActiveDOMObject()
[1:1:0831/174904:113000213207:INFO:ElementVisibilityObserver.cpp(28)] ElementVisibilityObserver::ElementVisibilityObserver()
[1:1:0831/174904:113000213262:INFO:IntersectionObserver.cpp(188)] IntersectionObserver::IntersectionObserver()
[1:1:0831/174904:113000213323:INFO:IntersectionObservation.cpp(23)] IntersectionObservation::IntersectionObservation()
[1:1:0831/174904:113000218940:INFO:Document.cpp(458)] Document::Document()
[1:1:0831/174904:113000219035:INFO:ActiveDOMObject.cpp(40)] ActiveDOMObject::ActiveDOMObject()
[1:1:0831/174904:113000219090:INFO:ActiveDOMObject.cpp(40)] ActiveDOMObject::ActiveDOMObject()
[1:1:0831/174904:113000231243:INFO:HTMLMediaElement.cpp(478)] HTMLMediaElement::dispose()
[1:1:0831/174904:113000231337:INFO:ActiveDOMObject.cpp(47)] ActiveDOMObject::~ActiveDOMObject()
[1:1:0831/174904:113000231391:INFO:ActiveDOMObject.cpp(47)] ActiveDOMObject::~ActiveDOMObject()
[1:1:0831/174904:113000231438:INFO:ActiveDOMObject.cpp(47)] ActiveDOMObject::~ActiveDOMObject()
[1:1:0831/174904:113000231483:INFO:ActiveDOMObject.cpp(47)] ActiveDOMObject::~ActiveDOMObject()
[1:1:0831/174904:113000231577:INFO:ElementVisibilityObserver.cpp(33)] ElementVisibilityObserver::~ElementVisibilityObserver()
[1:1:0831/174904:113000231632:INFO:IntersectionObservation.cpp(28)] IntersectionObservation::~IntersectionObservation()
[1:1:0831/174904:113000231672:INFO:ElementVisibilityObserver.cpp(33)] ElementVisibilityObserver::~ElementVisibilityObserver()
[1:1:0831/174904:113000231713:INFO:IntersectionObservation.cpp(28)] IntersectionObservation::~IntersectionObservation()
[1:1:0831/174904:113000231773:INFO:AutoplayUmaHelper.cpp(45)] AutoplayUmaHelper::~AutoplayUmaHelper()
[1:1:0831/174904:113000231873:INFO:ActiveDOMObject.cpp(47)] ActiveDOMObject::~ActiveDOMObject()
[1:1:0831/174904:113000231982:INFO:IntersectionObserver.cpp(218)] IntersectionObserver::~IntersectionObserver()
[1:1:0831/174904:113000232096:INFO:Document.cpp(516)] Document::~Document()
[1:1:0831/174904:113000232151:INFO:HTMLMediaElement.cpp(466)] HTMLMediaElement::~HTMLMediaElement()
[1:1:0831/174904:113000232204:INFO:ActiveDOMObject.cpp(47)] ActiveDOMObject::~ActiveDOMObject()
[1:1:0831/174904:113000235349:INFO:HTMLMediaElement.cpp(478)] HTMLMediaElement::dispose()
[1:1:0831/174904:113000235415:INFO:ActiveDOMObject.cpp(47)] ActiveDOMObject::~ActiveDOMObject()
[1:1:0831/174904:113000235499:INFO:AutoplayUmaHelper.cpp(45)] AutoplayUmaHelper::~AutoplayUmaHelper()
[1:1:0831/174904:113000235551:INFO:IntersectionObserverController.cpp(30)] IntersectionObserverController::~IntersectionObserverController()
[1:1:0831/174904:113000235594:INFO:ActiveDOMObject.cpp(47)] ActiveDOMObject::~ActiveDOMObject()
[1:1:0831/174904:113000235643:INFO:ActiveDOMObject.cpp(47)] ActiveDOMObject::~ActiveDOMObject()
[1:1:0831/174904:113000235701:INFO:IntersectionObserver.cpp(218)] IntersectionObserver::~IntersectionObserver()
[1:1:0831/174904:113000235755:INFO:Document.cpp(516)] Document::~Document()
[1:1:0831/174904:113000235814:INFO:HTMLMediaElement.cpp(466)] HTMLMediaElement::~HTMLMediaElement()
[1:1:0831/174904:113000235857:INFO:ActiveDOMObject.cpp(47)] ActiveDOMObject::~ActiveDOMObject()

Steps to repro:

1. Set up and make a release build

2. third_party/WebKit/Tools/Scripts/run-webkit-tests -t LinuxRel media/autoplay-muted.html --enable-leak-detection

Also, you can minimize autoplay-muted.html by removing all other tests except for the first one.

Steps to repro:

0. Apply patch https://codereview.chromium.org/2331893003/

The leak is no longer repro on ToT. Seems it has been fixed somewhere. I'll land the patch again and see if the bots are still reporting leaks.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/d791630a5f638c81b21284a7a8a22778c315cdde

commit d791630a5f638c81b21284a7a8a22778c315cdde
Author: zqzhang <zqzhang@chromium.org>
Date: Tue Sep 13 09:50:42 2016

Reland "Record the offscreen playing duration of autoplaying muted videos"

Seems the memory leak has already been fixed somewhere. Relanding this CL.

BUG= 617681 , 640195 
TBR=mlamouri@chromium.org,isherman@chromium.org

Review-Url: https://codereview.chromium.org/2331893003
Cr-Commit-Position: refs/heads/master@{#418208}

[modify] https://crrev.com/d791630a5f638c81b21284a7a8a22778c315cdde/third_party/WebKit/LayoutTests/media/video-autoplay-experiment-modes-expected.txt
[modify] https://crrev.com/d791630a5f638c81b21284a7a8a22778c315cdde/third_party/WebKit/Source/core/html/AutoplayUmaHelper.cpp
[modify] https://crrev.com/d791630a5f638c81b21284a7a8a22778c315cdde/third_party/WebKit/Source/core/html/AutoplayUmaHelper.h
[modify] https://crrev.com/d791630a5f638c81b21284a7a8a22778c315cdde/tools/metrics/histograms/histograms.xml

It sounds like this is fixed. Somehow.