@l446240525: Could you please provide us the Steps to reproduce, Expected & Actual results to triage this issue from our side. 

Also, please provide us the sample file to repro this issue, which would help us in triaging it further.

Thank you.

@rnimmagadda see https://bugs.chromium.org/p/chromium/issues/detail?id=540528#c52 Dev team will look into this issue.

@l446240525: Do you want me to merge this issue into - 540528 ?

@rnimmagadda: No, please label this issue as a feature request.

Thank you for providing more feedback. Adding requester "rnimmagadda@chromium.org" for another review and adding "Needs-Review" label for tracking.

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

Could someone from DevTools team please look into this feature request.

Thank you.

mpb@, if you are implementing Interaction Observers, would adding a warning be something under your attention?

+szager, who did the current IO implementation. 

I have a patch in-flight to add the warning:

https://codereview.chromium.org/2048853002/

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/33e0e1347fd2172236dc961805e956fecc159b80

commit 33e0e1347fd2172236dc961805e956fecc159b80
Author: szager <szager@chromium.org>
Date: Thu Jun 09 05:46:29 2016

IntersectionObserver: Warn when target is not a descendant of root.

BUG= 617393 
R=eae@chromium.org

Review-Url: https://codereview.chromium.org/2048853002
Cr-Commit-Position: refs/heads/master@{#398794}

[add] https://crrev.com/33e0e1347fd2172236dc961805e956fecc159b80/third_party/WebKit/LayoutTests/intersection-observer/containing-block-warning-expected.txt
[add] https://crrev.com/33e0e1347fd2172236dc961805e956fecc159b80/third_party/WebKit/LayoutTests/intersection-observer/containing-block-warning.html
[modify] https://crrev.com/33e0e1347fd2172236dc961805e956fecc159b80/third_party/WebKit/Source/core/dom/IntersectionObserver.cpp

Nice job, szager@!

Hello, I did not set the root elem, but the chrome still give this warning: target element is not a descendant of root, is this wrong? I did not understand.