Tested the issue on chrome#beta #60.0.3112.40 #Dev 61.0.3135.4 & Canary 56.0.2891.0 in Ubuntu 14.04 and was able to reproduce the issue.

Observations:
1.Pixel(250*250)resize observer is not visible in latest canary,Beta and older versions(M-50,M-45,M-35 & M-30) but visible in Dev build(61.0.3135.4).Please find the screen shot for reference.

This is a Non-Regression issue since seeing this from M30 #30.0.1549.0, Making the status to Untriaged so that the issue would get addressed.

Note : Able to reproduce the issue in MAC 10.12 and Win 10.0.

Thank you.

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	735830(Dev).png 64.1 KB View Download

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	735830(Beta).png 47.7 KB View Download

Confirmed. Starting work.

@bashi:
The root cause of this bug is that javascript callback gets garbage collected, and ResizeObserverCallback.callback_ is null. This is why notifications stop.

This bug was introduced in your CL 
https://chromium-review.googlesource.com/c/515183

I am not an Oilpan expert, so I am not sure what the right fix is. To me, it looks like the problem is this:

ResizeObserverCallback is supposed to be kept alive by reference from ResizeObserver. This used to work:

Working code had:
Member<ResizeObserverCallback> callback_;

New code has:
const TraceWrapperMember<ResizeObserverCallback> callback_;
const Member<Delegate> delegate_;

For some reason, the new code is not keeping ResizeObserverCallback.callback_ alive.

Can you help?

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/a5d05f5066da6c64cec104cf766e566273a471be

commit a5d05f5066da6c64cec104cf766e566273a471be
Author: Aleks Totic <atotic@chromium.org>
Date: Wed Aug 09 21:05:40 2017

Added test case to detect garbage collection problems

Bug:  735830 
Change-Id: I94d3777b2c242b3ff9e496649472d70b46e43fd2
Reviewed-on: https://chromium-review.googlesource.com/609209
Reviewed-by: Emil A Eklund <eae@chromium.org>
Commit-Queue: Aleks Totic <atotic@chromium.org>
Cr-Commit-Position: refs/heads/master@{#493136}
[modify] https://crrev.com/a5d05f5066da6c64cec104cf766e566273a471be/third_party/WebKit/LayoutTests/TestExpectations
[add] https://crrev.com/a5d05f5066da6c64cec104cf766e566273a471be/third_party/WebKit/LayoutTests/resize-observer/garbage_collection.html

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/850ef295da299a0912606a9244494f03eb113d5e

commit 850ef295da299a0912606a9244494f03eb113d5e
Author: Kenichi Ishibashi <bashi@chromium.org>
Date: Thu Aug 10 05:10:38 2017

ElementRareData should trace ResizeObservers

As the spec said[1], we have to make sure that ResizeObserver remains
alive when the observer is observing a target. Before this CL we don't
trace ResizeObserver from ElementRareData which caused miscollection
of ResizeObserver.

[1] https://wicg.github.io/ResizeObserver/#lifetime

BUG= 735830 

Change-Id: I66c7a7544936345d27d81bde741df474abc17097
Reviewed-on: https://chromium-review.googlesource.com/608982
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Commit-Queue: Kenichi Ishibashi <bashi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#493241}
[modify] https://crrev.com/850ef295da299a0912606a9244494f03eb113d5e/third_party/WebKit/LayoutTests/TestExpectations
[modify] https://crrev.com/850ef295da299a0912606a9244494f03eb113d5e/third_party/WebKit/Source/core/dom/ElementRareData.cpp