Good Build:51.0.2693.2
Bad Build:51.0.2695.0

NOTE: Issue working fine in 51.0.2693.2 dev i.e no transition of toolbar is seen on scrolling using mouse wheel. 

In 51.0.2694.0 we have an issue of nothing scrolls on using mouse wheel in pdf.[ Issue 598658 ] Hence considered that too as good build.

CHANGELOG URL: https://chromium.googlesource.com/chromium/src/+log/96b33a5c49cfb46db5756ea80d52ba5d42eae398..fe1e90eeacdc473325519df9c556d1cffa5db3a0

Suspecting https://codereview.chromium.org/1841053002 from changelog.

@dtapuska: please confirm the issue and help in re-assigning if it is not related to your change.

I get the toolbar to disappear on stable 49.0.2623.110 (Ubuntu 14.04) as well.

It will disappear after a lot of scrolling up and down.

Could it be that it is disappearing a little earlier now?

sc00335628@

See the attached video on 49.0.2623.110. I think it depends on if you mouse wheel and then move your mouse a little.

Can you confirm that you reproduce this in 49 as well?

Deleted: 464557-3-1.ogv 3.7 MB

464557-3-1.ogv 3.7 MB Download

@dtapuska: It is not about the disappearance of toolbar.

Transition/unwanted flickering of toolbar[On top of pdf page] is seen on continuous scrolling using mouse wheel.

Please find the attached video.

Deleted: Issue_599340.ogv 7.4 MB

Issue_599340.ogv 7.4 MB Download

Checked the issue on 51.0.2701.0 Ubuntu 14.04 and is still reproducible.

Open above pdf page and try to scroll continuously up and down[scroll only small area] and observe flickering of toolbar.

small observation: Toolbar flickers when scrollbar touches top arrow while scrolling using mouse wheel.

For same bisect range another issue seen on pdf scrolling with same culprit.

Steps to reproduce:
1. Open any pdf page >> Place mouse pointer on pdf toolbar >> Scroll some part of pdf page[Don't scroll full page] continuously using mouse wheel[Please refer video]

Expected: Pdf page should not vanish on continuous scrolling.
Actual: Instead pdf page vanishes on scrolling only some part of page up and down continuously.

Deleted: Actual_pdf.ogv 5.5 MB

Actual_pdf.ogv 5.5 MB Download

Deleted: Expected_pdf.ogv 13.9 MB

Expected_pdf.ogv 13.9 MB Download

sc00335628@ can you try with --disable-threaded-scrolling I wasn't able to reproduce this.

ericrk@ do you think this is a duplicate of  issue 599682 

As per comment#6 : Checked the issues[comment#0 and comment#5] on 51.0.2701.0 Ubuntu 14.04 by disabling threaded scrolling from chrome://flags and unable to reproduce it with that flag disabled.

Issue is seen only when threaded scrolling flag is enabled.

 Issue 603809  has been merged into this issue.

Adding stable blocker as this is regressed on M51.

wangxianzhu@ do you know if this is fixed with your patch for  issue 599682 ?

sc00335628@techmahindra.com; Are you still able to reproduce this in dev?

Not reproduced on ToT.

sc00335628@techmahindra.com can you verify?

Unable to reproduce the issue on win8.1 chrome version 52.0.2713.0 and dev 51.0.2704.19 - unwanted transition of toolbar is not visible

Please find the screencast

sc00335628@techmahindra.com, Can you please recheck and update the thread.

Deleted: Recording #32.mp4 2.7 MB

Recording #32.mp4 2.7 MB Download

Checked the issue on 52.0.2713.0 dev and no longer able to reproduce it.

i.e No transition of toolbar is seen and pdf page doesn't vanish on scrolling.

Marking as duplicate so merges can be tracked correctly.