Able to reproduce the issue on Linux Ubuntu 14.04 using chrome version 61.0.3150.0

Able to reproduce the issue on Ubuntu 14.04 using chrome latest Canary-61.0.3150.0.
Manual bisect info:
-------------------
Good build: 59.0.3055.3-Revision-460255
Bad Build: 59.0.3056.0 -Revision-460603

Per revision bisect info:
------------------------
You are probably looking for a change made after 460366 (known good), but no later than 460367 (first known bad).
CHANGELOG URL:
The script might not always return single CL as suspectas some perf builds might get missing due to failure.
https://chromium.googlesource.com/chromium/src/+log/88e50721bcd19d719d3417ac9c3f86dd87439268..bca2d029eea47a55324d505a88329cd4112de03d

bokan@Could you please take a look.

Thanks..!!

This isn't a regression but my patch did make it more visible. See on a page like http://www.onemilescroll.com/

1. Scroll all the way to the end
2. Try to drag the thumb once its at the end

It seems that we have some inaccuracy that gets compounded the further we scroll. I'll keep investigating 

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/9e21c73c78295efc419bd4f182a44345fe29237d

commit 9e21c73c78295efc419bd4f182a44345fe29237d
Author: David Bokan <bokan@chromium.org>
Date: Thu Aug 03 16:46:30 2017

Fix overlay scrollbar at huge scroll offsets

The overlay scrollbar ThumbPosition method was losing precision at very
high scroll offsets. This would cause it to drift away from where we
actually show the thumb from the compositor so the hit testing would be
unreliable.

Looking at this method, there's no reason it should need to be any
different from the base class ScrollbarTheme::ThumbPosition which is
robust under high scroll offsets so the solution here is to simply
remove the override. Less code, less bugs.

Bug:  739668 
Change-Id: Ib90152d989931cd0bcc0bddfb226d97d577ce575
Reviewed-on: https://chromium-review.googlesource.com/598734
Reviewed-by: Dave Tapuska <dtapuska@chromium.org>
Reviewed-by: Jeremy Roman <jbroman@chromium.org>
Commit-Queue: David Bokan <bokan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#491766}
[modify] https://crrev.com/9e21c73c78295efc419bd4f182a44345fe29237d/third_party/WebKit/Source/core/layout/ScrollbarsTest.cpp
[modify] https://crrev.com/9e21c73c78295efc419bd4f182a44345fe29237d/third_party/WebKit/Source/platform/scroll/ScrollbarThemeOverlay.cpp
[modify] https://crrev.com/9e21c73c78295efc419bd4f182a44345fe29237d/third_party/WebKit/Source/platform/scroll/ScrollbarThemeOverlay.h

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/b0e8b8715cac01e63d2b4fb5c064fa29e5ce4754

commit b0e8b8715cac01e63d2b4fb5c064fa29e5ce4754
Author: Luna Lu <loonybear@chromium.org>
Date: Thu Aug 03 18:23:40 2017

Revert "Fix overlay scrollbar at huge scroll offsets"

This reverts commit 9e21c73c78295efc419bd4f182a44345fe29237d.

Reason for revert: suspect causing WebKit Android (Nexus 4) to fail on webkit_unit_tests
https://uberchromegw.corp.google.com/i/chromium.webkit/builders/WebKit%20Android%20%28Nexus4%29/builds/67957

Original change's description:
> Fix overlay scrollbar at huge scroll offsets
> 
> The overlay scrollbar ThumbPosition method was losing precision at very
> high scroll offsets. This would cause it to drift away from where we
> actually show the thumb from the compositor so the hit testing would be
> unreliable.
> 
> Looking at this method, there's no reason it should need to be any
> different from the base class ScrollbarTheme::ThumbPosition which is
> robust under high scroll offsets so the solution here is to simply
> remove the override. Less code, less bugs.
> 
> Bug:  739668 
> Change-Id: Ib90152d989931cd0bcc0bddfb226d97d577ce575
> Reviewed-on: https://chromium-review.googlesource.com/598734
> Reviewed-by: Dave Tapuska <dtapuska@chromium.org>
> Reviewed-by: Jeremy Roman <jbroman@chromium.org>
> Commit-Queue: David Bokan <bokan@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#491766}

TBR=bokan@chromium.org,jbroman@chromium.org,dtapuska@chromium.org

Change-Id: I44f227bc5956899ff43e7c6d96e7c5596666ae36
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug:  739668 
Reviewed-on: https://chromium-review.googlesource.com/600848
Reviewed-by: Luna Lu <loonybear@chromium.org>
Commit-Queue: Luna Lu <loonybear@chromium.org>
Cr-Commit-Position: refs/heads/master@{#491798}
[modify] https://crrev.com/b0e8b8715cac01e63d2b4fb5c064fa29e5ce4754/third_party/WebKit/Source/core/layout/ScrollbarsTest.cpp
[modify] https://crrev.com/b0e8b8715cac01e63d2b4fb5c064fa29e5ce4754/third_party/WebKit/Source/platform/scroll/ScrollbarThemeOverlay.cpp
[modify] https://crrev.com/b0e8b8715cac01e63d2b4fb5c064fa29e5ce4754/third_party/WebKit/Source/platform/scroll/ScrollbarThemeOverlay.h

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/d88adacb7803429007f81f62824b60c0f4b4358a

commit d88adacb7803429007f81f62824b60c0f4b4358a
Author: David Bokan <bokan@chromium.org>
Date: Tue Aug 15 00:21:03 2017

Reland: Fix overlay scrollbar at huge scroll offsets

Raland note: This was landed previously in r491766 but reverted in
r491798 because the newly added test was failing on Android. On Android
the scrollbar margin was causing unexpected values in the test so this
patch modifies the test to a common value for margin (0).

The overlay scrollbar ThumbPosition method was losing precision at very
high scroll offsets. This would cause it to drift away from where we
actually show the thumb from the compositor so the hit testing would be
unreliable.

Looking at this method, there's no reason it should need to be any
different from the base class ScrollbarTheme::ThumbPosition which is
robust under high scroll offsets so the solution here is to simply
remove the override. Less code, less bugs.

Bug:  739668 
Change-Id: Idaa61cd225b6cf67677dee364eb4fefed2ef4890
TBR: dtapuska@chromium.org, jbroman@chromium.org
Reviewed-on: https://chromium-review.googlesource.com/614614
Reviewed-by: David Bokan <bokan@chromium.org>
Commit-Queue: David Bokan <bokan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#494260}
[modify] https://crrev.com/d88adacb7803429007f81f62824b60c0f4b4358a/third_party/WebKit/Source/core/layout/ScrollbarsTest.cpp
[modify] https://crrev.com/d88adacb7803429007f81f62824b60c0f4b4358a/third_party/WebKit/Source/platform/scroll/ScrollbarThemeOverlay.cpp
[modify] https://crrev.com/d88adacb7803429007f81f62824b60c0f4b4358a/third_party/WebKit/Source/platform/scroll/ScrollbarThemeOverlay.h

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/eb6afe80a27b824c56d1698d010f79997bb9ebfa

commit eb6afe80a27b824c56d1698d010f79997bb9ebfa
Author: Reilly Grant <reillyg@chromium.org>
Date: Tue Aug 15 17:19:37 2017

Revert "Reland: Fix overlay scrollbar at huge scroll offsets"

This reverts commit d88adacb7803429007f81f62824b60c0f4b4358a.

Reason for revert: use-of-uninitialized-value detected by MSan bots: https://uberchromegw.corp.google.com/i/chromium.webkit/builders/WebKit%20Linux%20Trusty%20MSAN/builds/2578

Original change's description:
> Reland: Fix overlay scrollbar at huge scroll offsets
> 
> Raland note: This was landed previously in r491766 but reverted in
> r491798 because the newly added test was failing on Android. On Android
> the scrollbar margin was causing unexpected values in the test so this
> patch modifies the test to a common value for margin (0).
> 
> The overlay scrollbar ThumbPosition method was losing precision at very
> high scroll offsets. This would cause it to drift away from where we
> actually show the thumb from the compositor so the hit testing would be
> unreliable.
> 
> Looking at this method, there's no reason it should need to be any
> different from the base class ScrollbarTheme::ThumbPosition which is
> robust under high scroll offsets so the solution here is to simply
> remove the override. Less code, less bugs.
> 
> Bug:  739668 
> Change-Id: Idaa61cd225b6cf67677dee364eb4fefed2ef4890
> TBR: dtapuska@chromium.org, jbroman@chromium.org
> Reviewed-on: https://chromium-review.googlesource.com/614614
> Reviewed-by: David Bokan <bokan@chromium.org>
> Commit-Queue: David Bokan <bokan@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#494260}

TBR=bokan@chromium.org,jbroman@chromium.org,dtapuska@chromium.org

Change-Id: Ie67748e47237ed9b64048e32bc10884e29afbace
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug:  739668 
Reviewed-on: https://chromium-review.googlesource.com/615045
Reviewed-by: Reilly Grant <reillyg@chromium.org>
Commit-Queue: Reilly Grant <reillyg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#494424}
[modify] https://crrev.com/eb6afe80a27b824c56d1698d010f79997bb9ebfa/third_party/WebKit/Source/core/layout/ScrollbarsTest.cpp
[modify] https://crrev.com/eb6afe80a27b824c56d1698d010f79997bb9ebfa/third_party/WebKit/Source/platform/scroll/ScrollbarThemeOverlay.cpp
[modify] https://crrev.com/eb6afe80a27b824c56d1698d010f79997bb9ebfa/third_party/WebKit/Source/platform/scroll/ScrollbarThemeOverlay.h

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/ddd3cd782a767148b44c0e83e381e373b3d1f255

commit ddd3cd782a767148b44c0e83e381e373b3d1f255
Author: Paul Meyer <paulmeyer@chromium.org>
Date: Tue Aug 15 18:27:36 2017

Revert "Reland: Fix overlay scrollbar at huge scroll offsets"

This reverts commit d88adacb7803429007f81f62824b60c0f4b4358a.

Reason for revert: Suspected cause of webkit_unit_tests failing on chromium.webkit/WebKit Linux Trusty MSAN.

Original change's description:
> Reland: Fix overlay scrollbar at huge scroll offsets
> 
> Raland note: This was landed previously in r491766 but reverted in
> r491798 because the newly added test was failing on Android. On Android
> the scrollbar margin was causing unexpected values in the test so this
> patch modifies the test to a common value for margin (0).
> 
> The overlay scrollbar ThumbPosition method was losing precision at very
> high scroll offsets. This would cause it to drift away from where we
> actually show the thumb from the compositor so the hit testing would be
> unreliable.
> 
> Looking at this method, there's no reason it should need to be any
> different from the base class ScrollbarTheme::ThumbPosition which is
> robust under high scroll offsets so the solution here is to simply
> remove the override. Less code, less bugs.
> 
> Bug:  739668 
> Change-Id: Idaa61cd225b6cf67677dee364eb4fefed2ef4890
> TBR: dtapuska@chromium.org, jbroman@chromium.org
> Reviewed-on: https://chromium-review.googlesource.com/614614
> Reviewed-by: David Bokan <bokan@chromium.org>
> Commit-Queue: David Bokan <bokan@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#494260}

TBR=bokan@chromium.org,jbroman@chromium.org,dtapuska@chromium.org

Change-Id: Ic28fe46ffa103d2a5100303e66c1a74c907ced08
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug:  739668 
Reviewed-on: https://chromium-review.googlesource.com/615544
Reviewed-by: Paul Meyer <paulmeyer@chromium.org>
Commit-Queue: Paul Meyer <paulmeyer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#494454}

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/bf42d2a12f0e26753d441d507d61b150c4a541c7

commit bf42d2a12f0e26753d441d507d61b150c4a541c7
Author: David Bokan <bokan@chromium.org>
Date: Tue Aug 15 19:25:01 2017

Re-Reland: Fix overlay scrollbar at huge scroll offsets

Rereland node: This was again landed in r494260 and reverted in
r494424 due to a use-of-uninitialized in the test. This patch
initializes all the values in the ScrollbarStyle struct.

Reland note: This was landed previously in r491766 but reverted in
r491798 because the newly added test was failing on Android. On Android
the scrollbar margin was causing unexpected values in the test so this
patch modifies the test to a common value for margin (0).

The overlay scrollbar ThumbPosition method was losing precision at very
high scroll offsets. This would cause it to drift away from where we
actually show the thumb from the compositor so the hit testing would be
unreliable.

Looking at this method, there's no reason it should need to be any
different from the base class ScrollbarTheme::ThumbPosition which is
robust under high scroll offsets so the solution here is to simply
remove the override. Less code, less bugs.

Bug:  739668 
TBR: dtapuska@chromium.org,jbroman@chromium.org
Change-Id: Ib0a306a1dc6e007a6f4a48a31953eb8bbd098775
Reviewed-on: https://chromium-review.googlesource.com/614758
Reviewed-by: David Bokan <bokan@chromium.org>
Commit-Queue: David Bokan <bokan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#494491}
[modify] https://crrev.com/bf42d2a12f0e26753d441d507d61b150c4a541c7/third_party/WebKit/Source/core/layout/ScrollbarsTest.cpp
[modify] https://crrev.com/bf42d2a12f0e26753d441d507d61b150c4a541c7/third_party/WebKit/Source/platform/scroll/ScrollbarThemeOverlay.cpp
[modify] https://crrev.com/bf42d2a12f0e26753d441d507d61b150c4a541c7/third_party/WebKit/Source/platform/scroll/ScrollbarThemeOverlay.h