Able to reproduce the issue on MAC 10.12.1 and is a regression broken in M56. Below are the bisect details for the same:

Good Build : 56.0.2886.0
Bad Build : 56.0.2888.0

Bisect URL: https://chromium.googlesource.com/chromium/src/+/50535c63a1e96b5078bee3724e8cf3b7922b686a
Change log: https://chromium.googlesource.com/chromium/src/+/3c806bffd
Review-Url: https://codereview.chromium.org/2411193002

@ chrishtr: Assigning to you, kindly have a look into it. Please help us to find an owner if not with respect to your change.

Also adding release block label, please undo if not the case.

Thanks.!

I can't reproduce this on 56.0.2914.3 / OS X 10.12.1 retina. or on 56.0.2920.0 / OS X 10.12.1 retina.

Testers, please test again on those versions.

Able to reproduce the issue on MAC Retina Pro 10.12.1 Intel HD Graphics 4000 1536 MB using chrome version 57.0.2926.0.Click on top of scroll bar and drag the scroll bar using mouse observed that scroll bar gets stuck.but issue is not consistently reproducible here also(frequency 3/5).

chrishtr@ Could you please look into this issue.

Thanks,

I can reproduce on Chrome Canary / Mac, but not Chromium ToT. Tried with trackpad
and mouse, and both are broken on Canary but work at ToT. Will try again in a few
days.

Now I can't reproduce on Canary. Maybe a commit in the last week fixed this issue.
Will bisect.

Bisect results:

https://chromium.googlesource.com/chromium/src/+log/979c4d82518fda1ea8182a7368da152b6bd38088..1ebcb4fa66e336bcbd59652c62d5e6e322ab5249

I think it was fixed by:

https://chromium.googlesource.com/chromium/src/+/fd7cfb578fb058ee68c19051fb1ecd564b563f73

Checking now.

Confirmed, this fixed it.

Thanks for the great investigation! I'm going to mark this as a blocker for  Issue 605219  so we make sure we don't regress it if we attempt the fix again.

Confirmed that this is brought back by turning on chrome::ShouldUseFullSizeContentView() ( issue 605219 ), but does *not* repro if I just enable Auto Layout ( issue 695577 ).

CL in progress: https://chromium-review.googlesource.com/c/566030/

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/45f7994fbcf0e40e02e4c4823a07b9b6ef28a325

commit 45f7994fbcf0e40e02e4c4823a07b9b6ef28a325
Author: Sidney San Martín <sdy@chromium.org>
Date: Tue Jul 11 07:05:57 2017

Enable ShouldUseFullSizeContentView().

Also fixes the known issues with enabling it:

- crbug/665787: The tab background view was added in front of the content and
  blocked interaction with the top of the scroll bar when the toolbar was
  hidden. It's now inserted behind the content, like before.

- crbug/655112: FramedBrowserWindowTest.DoesHideTitle took screenshots of the
  frame view, which gets drawn using a different (layer-backed?) path when
  NSFullSizeContentViewWindowMask is on. The test now calls -[CATransaction
  flush] before taking each screenshot, and uses a different API to screenshot
  the whole window instead of trying to grab just the frame view by accessing
  the content view's superview.

Bug:  605219 ,  655112 ,  665787 ,  730679 ,  734713 ,  737206 
Change-Id: Id78c21aff6748e02fd4b3e461c77ef9f7454d744
Reviewed-on: https://chromium-review.googlesource.com/566030
Commit-Queue: Sidney San Martin <sdy@chromium.org>
Reviewed-by: Trent Apted <tapted@chromium.org>
Cr-Commit-Position: refs/heads/master@{#485544}
[modify] https://crrev.com/45f7994fbcf0e40e02e4c4823a07b9b6ef28a325/chrome/browser/ui/cocoa/browser_window_layout.mm
[modify] https://crrev.com/45f7994fbcf0e40e02e4c4823a07b9b6ef28a325/chrome/browser/ui/cocoa/framed_browser_window_unittest.mm
[modify] https://crrev.com/45f7994fbcf0e40e02e4c4823a07b9b6ef28a325/chrome/browser/ui/cocoa/tabs/tab_window_controller.mm

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/685e99063e6bac1d4417829ec3b6abdcb918caf6

commit 685e99063e6bac1d4417829ec3b6abdcb918caf6
Author: Keishi Hattori <keishi@chromium.org>
Date: Tue Jul 11 08:55:01 2017

Revert "Enable ShouldUseFullSizeContentView()."

This reverts commit 45f7994fbcf0e40e02e4c4823a07b9b6ef28a325.

Reason for revert: Broke BrowserWindowControllerTest.UsesAutoLayout

Original change's description:
> Enable ShouldUseFullSizeContentView().
> 
> Also fixes the known issues with enabling it:
> 
> - crbug/665787: The tab background view was added in front of the content and
>   blocked interaction with the top of the scroll bar when the toolbar was
>   hidden. It's now inserted behind the content, like before.
> 
> - crbug/655112: FramedBrowserWindowTest.DoesHideTitle took screenshots of the
>   frame view, which gets drawn using a different (layer-backed?) path when
>   NSFullSizeContentViewWindowMask is on. The test now calls -[CATransaction
>   flush] before taking each screenshot, and uses a different API to screenshot
>   the whole window instead of trying to grab just the frame view by accessing
>   the content view's superview.
> 
> Bug:  605219 ,  655112 ,  665787 ,  730679 ,  734713 ,  737206 
> Change-Id: Id78c21aff6748e02fd4b3e461c77ef9f7454d744
> Reviewed-on: https://chromium-review.googlesource.com/566030
> Commit-Queue: Sidney San Martin <sdy@chromium.org>
> Reviewed-by: Trent Apted <tapted@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#485544}

TBR=tapted@chromium.org,shrike@chromium.org,sdy@chromium.org

Change-Id: I00b73bc5d2d5607736ddc81b9ae81ec65527ebad
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug:  605219 ,  655112 ,  665787 ,  730679 ,  734713 ,  737206 
Reviewed-on: https://chromium-review.googlesource.com/566898
Reviewed-by: Keishi Hattori <keishi@chromium.org>
Commit-Queue: Keishi Hattori <keishi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#485564}
[modify] https://crrev.com/685e99063e6bac1d4417829ec3b6abdcb918caf6/chrome/browser/ui/cocoa/browser_window_layout.mm
[modify] https://crrev.com/685e99063e6bac1d4417829ec3b6abdcb918caf6/chrome/browser/ui/cocoa/framed_browser_window_unittest.mm
[modify] https://crrev.com/685e99063e6bac1d4417829ec3b6abdcb918caf6/chrome/browser/ui/cocoa/tabs/tab_window_controller.mm

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/a20a025fb10592190b5b3bc90fd627c45c76676a

commit a20a025fb10592190b5b3bc90fd627c45c76676a
Author: Sidney San Martín <sdy@chromium.org>
Date: Tue Jul 11 18:39:06 2017

Enable ShouldUseFullSizeContentView().

Also fixes the known issues with enabling it:

- crbug/665787: The tab background view was added in front of the content and
  blocked interaction with the top of the scroll bar when the toolbar was
  hidden. It's now inserted behind the content, like before.

- crbug/655112: FramedBrowserWindowTest.DoesHideTitle took screenshots of the
  frame view, which gets drawn using a different (layer-backed?) path when
  NSFullSizeContentViewWindowMask is on. The test now calls -[CATransaction
  flush] before taking each screenshot, and uses a different API to screenshot
  the whole window instead of trying to grab just the frame view by accessing
  the content view's superview.

This is a re-land of r485544 (reverted in r485564) with a test fix for
BrowserWindowControllerTest.UsesAutoLayout.

Bug:  605219 ,  655112 ,  665787 ,  730679 ,  734713 ,  737206 
Change-Id: I59c03e90b30613285df89a1b3694f36de3f1a7d8
Reviewed-on: https://chromium-review.googlesource.com/567205
Reviewed-by: Elly Fong-Jones <ellyjones@chromium.org>
Commit-Queue: Sidney San Martin <sdy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#485682}
[modify] https://crrev.com/a20a025fb10592190b5b3bc90fd627c45c76676a/chrome/browser/ui/cocoa/browser_window_controller_unittest.mm
[modify] https://crrev.com/a20a025fb10592190b5b3bc90fd627c45c76676a/chrome/browser/ui/cocoa/browser_window_layout.mm
[modify] https://crrev.com/a20a025fb10592190b5b3bc90fd627c45c76676a/chrome/browser/ui/cocoa/framed_browser_window_unittest.mm
[modify] https://crrev.com/a20a025fb10592190b5b3bc90fd627c45c76676a/chrome/browser/ui/cocoa/tabs/tab_window_controller.mm