Just double-checked this. It is still present in 54.0.2824.0 though the dropdown I used above doesn't show the bug, so it must be finicky in some way.

I attached a screenshot of a different dropdown that does exhibit the bug.

Deleted: dropdown-blackborders.PNG 18.5 KB

	dropdown-blackborders.PNG 18.5 KB View Download

Repros on most dropdowns on http://www.roboform.com/filling-test-shopping-cart

I saw this issue with <input type=date> too.
I guess this is not a popup content rendering issue, but a paint/compositing off-by-one.
So the problem must be in third_party/WebKit/Source/web/WebPagePopupImpl.*, PageWidgetDelegate.*, or chromium compositor.

oshima: don't work on this right now. It requires some infrastructure work on Windows. See bug 668278.

I thought the border one is separate issue, no?

Yes, the border being wrong is separate from the font size being wrong from  bug 674666 . But we can't fix the border being wrong right now. The <select> dropdowns are positioned in DIPs even though Windows expects pixels, and so we lose some precision. This is an old issue.

so you're saying that the border is outside of the content?

Yes, it spawns a separate window so it can hover over and outside the main window.

I know it creates a window, but it doesn't automatically create a black border.
My question was where this black border comes from.

Ah yes, sorry. I'm not sure exactly why in this case, but the window's contents are aligned differently than the window. So the black border is area where we don't render anything.

It is a little odd, because you'd expect the window area and the contents to have the same precision loss. I could be wrong about this since kulshin@ was the one investigating it.

Ok, sounds like it's still worth looking into this, at least once. If this is indeed due to windows placement, yes, I agree that we need to wait.

linux has simiar issue, so I'll work on linux first.

Yep, it was just a bug, not positioning issue. I have a fix for linux, and I'd expect it will work for win too.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/0aafa24f1ad6b4331bdb65db12ffc1842ba69b1d

commit 0aafa24f1ad6b4331bdb65db12ffc1842ba69b1d
Author: oshima <oshima@chromium.org>
Date: Wed Jan 11 00:25:34 2017

Correctly update the popup window position

It was updating the child window instead.
This CL hooks up the bounds change to the desktop widget correctly.

BUG=612270
TEST=fixed test harness to do the correct check.

Review-Url: https://codereview.chromium.org/2583873002
Cr-Commit-Position: refs/heads/master@{#442741}

[modify] https://crrev.com/0aafa24f1ad6b4331bdb65db12ffc1842ba69b1d/content/browser/renderer_host/render_widget_host_view_aura.cc
[modify] https://crrev.com/0aafa24f1ad6b4331bdb65db12ffc1842ba69b1d/content/browser/renderer_host/render_widget_host_view_aura.h
[modify] https://crrev.com/0aafa24f1ad6b4331bdb65db12ffc1842ba69b1d/content/browser/renderer_host/render_widget_host_view_aura_unittest.cc
[modify] https://crrev.com/0aafa24f1ad6b4331bdb65db12ffc1842ba69b1d/ui/aura/window.cc
[modify] https://crrev.com/0aafa24f1ad6b4331bdb65db12ffc1842ba69b1d/ui/views/widget/desktop_aura/desktop_native_widget_aura_unittest.cc
[modify] https://crrev.com/0aafa24f1ad6b4331bdb65db12ffc1842ba69b1d/ui/views/widget/desktop_aura/desktop_screen_position_client.cc

Verified on windows 7 using chrome clang M57 #57.0.2979.2 and issue is fixed.

Navigated to the url provided in commeny #2 , and observed that no black border is seen on left and top edge of the dropdown input selction boxes.

Attached screencast for reference.

Adding TE-Verified labels.

Thanks!

Deleted: 612270.mp4 862 KB

	612270.mp4 862 KB View Download

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/2ba9b1f20d4f158b5cdeb359d9ab7d836e09858a

commit 2ba9b1f20d4f158b5cdeb359d9ab7d836e09858a
Author: malaykeshav <malaykeshav@chromium.org>
Date: Tue Mar 07 21:51:44 2017

Revert of Correctly update the popup window position (patchset #6 id:160001 of https://codereview.chromium.org/2583873002/ )

Reason for revert:
Breaking M57
crbug/698627

Original issue's description:
> Correctly update the popup window position
>
> It was updating the child window instead.
> This CL hooks up the bounds change to the desktop widget correctly.
>
> BUG=612270
> TEST=fixed test harness to do the correct check.
>
> Review-Url: https://codereview.chromium.org/2583873002
> Cr-Commit-Position: refs/heads/master@{#442741}
> Committed: https://chromium.googlesource.com/chromium/src/+/0aafa24f1ad6b4331bdb65db12ffc1842ba69b1d

TBR=sadrul@chromium.org,bsep@chromium.org,oshima@chromium.org
# Not skipping CQ checks because original CL landed more than 1 days ago.
BUG=612270,  698627 

Review-Url: https://codereview.chromium.org/2728293004
Cr-Commit-Position: refs/heads/master@{#455231}

[modify] https://crrev.com/2ba9b1f20d4f158b5cdeb359d9ab7d836e09858a/content/browser/renderer_host/render_widget_host_view_aura.cc
[modify] https://crrev.com/2ba9b1f20d4f158b5cdeb359d9ab7d836e09858a/content/browser/renderer_host/render_widget_host_view_aura.h
[modify] https://crrev.com/2ba9b1f20d4f158b5cdeb359d9ab7d836e09858a/content/browser/renderer_host/render_widget_host_view_aura_unittest.cc
[modify] https://crrev.com/2ba9b1f20d4f158b5cdeb359d9ab7d836e09858a/ui/aura/window.cc
[modify] https://crrev.com/2ba9b1f20d4f158b5cdeb359d9ab7d836e09858a/ui/views/widget/desktop_aura/desktop_native_widget_aura_unittest.cc
[modify] https://crrev.com/2ba9b1f20d4f158b5cdeb359d9ab7d836e09858a/ui/views/widget/desktop_aura/desktop_screen_position_client.cc

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/750f7aa5d49254312e77f3fc947acbe5d2927769

commit 750f7aa5d49254312e77f3fc947acbe5d2927769
Author: Steven Bennetts <stevenjb@chromium.org>
Date: Tue Mar 07 22:50:04 2017

Revert of Correctly update the popup window position (patchset #6 id:160001 of https://codereview.chromium.org/2583873002/ )

Reason for revert:
Breaking M57
crbug/698627

Original issue's description:
> Correctly update the popup window position
>
> It was updating the child window instead.
> This CL hooks up the bounds change to the desktop widget correctly.
>
> BUG=612270
> TEST=fixed test harness to do the correct check.
>
> Review-Url: https://codereview.chromium.org/2583873002
> Cr-Commit-Position: refs/heads/master@{#442741}
> Committed: https://chromium.googlesource.com/chromium/src/+/0aafa24f1ad6b4331bdb65db12ffc1842ba69b1d

TBR=sadrul@chromium.org,bsep@chromium.org,oshima@chromium.org
BUG=612270,  698627 

Review-Url: https://codereview.chromium.org/2728293004
Cr-Commit-Position: refs/heads/master@{#455231}
(cherry picked from commit 2ba9b1f20d4f158b5cdeb359d9ab7d836e09858a)

Review-Url: https://codereview.chromium.org/2732383002 .
Cr-Commit-Position: refs/branch-heads/2987@{#791}
Cr-Branched-From: ad51088c0e8776e8dcd963dbe752c4035ba6dab6-refs/heads/master@{#444943}

[modify] https://crrev.com/750f7aa5d49254312e77f3fc947acbe5d2927769/content/browser/renderer_host/render_widget_host_view_aura.cc
[modify] https://crrev.com/750f7aa5d49254312e77f3fc947acbe5d2927769/content/browser/renderer_host/render_widget_host_view_aura.h
[modify] https://crrev.com/750f7aa5d49254312e77f3fc947acbe5d2927769/content/browser/renderer_host/render_widget_host_view_aura_unittest.cc
[modify] https://crrev.com/750f7aa5d49254312e77f3fc947acbe5d2927769/ui/aura/window.cc
[modify] https://crrev.com/750f7aa5d49254312e77f3fc947acbe5d2927769/ui/views/widget/desktop_aura/desktop_native_widget_aura_unittest.cc
[modify] https://crrev.com/750f7aa5d49254312e77f3fc947acbe5d2927769/ui/views/widget/desktop_aura/desktop_screen_position_client.cc

Tested on windows 7 using chrome M57 #57.0.2924.87 and dark black line is observed on the drop down text field.

Attached screencast for reference.

Tested URL : http://www.roboform.com/filling-test-shopping-cart

@Could someone look into this and confirm if this is the expected behavior or any steps to consider for testing .

Thanks!

Deleted: 612270 (1).mp4 1.5 MB

	612270 (1).mp4 1.5 MB View Download

As mentioned in comment #20 , when it was tested on M57 #57.0.2979.2 using url "http://www.roboform.com/filling-test-shopping-cart" ,no black line was seen sorrounded by drop down text field , but in M57 #57.0.2924.87 , black line is seen  as attached in comment #24 .

Hence , adding needs-feedback to get it confirmed.

Thanks!

#24-25, the fix for this issue was reverted on trunk and M57 branch.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/a2b327d0b8e2935ba42f8f4b084c4afccfc6cbf3

commit a2b327d0b8e2935ba42f8f4b084c4afccfc6cbf3
Author: Jacob Dufault <jdufault@google.com>
Date: Mon Mar 13 18:55:57 2017

Revert of Correctly update the popup window position (patchset #6 id:160001 of https://codereview.chromium.org/2583873002/ )

Reason for revert:
Breaking M57
crbug/698627

Original issue's description:
> Correctly update the popup window position
>
> It was updating the child window instead.
> This CL hooks up the bounds change to the desktop widget correctly.
>
> BUG=612270
> TEST=fixed test harness to do the correct check.
>
> Review-Url: https://codereview.chromium.org/2583873002
> Cr-Commit-Position: refs/heads/master@{#442741}
> Committed: https://chromium.googlesource.com/chromium/src/+/0aafa24f1ad6b4331bdb65db12ffc1842ba69b1d

TBR=sadrul@chromium.org,bsep@chromium.org,oshima@chromium.org
BUG=612270,  698627 

Review-Url: https://codereview.chromium.org/2728293004
Cr-Commit-Position: refs/heads/master@{#455231}
(cherry picked from commit 2ba9b1f20d4f158b5cdeb359d9ab7d836e09858a)

Review-Url: https://codereview.chromium.org/2747723004 .
Cr-Commit-Position: refs/branch-heads/3029@{#159}
Cr-Branched-From: 939b32ee5ba05c396eef3fd992822fcca9a2e262-refs/heads/master@{#454471}

[modify] https://crrev.com/a2b327d0b8e2935ba42f8f4b084c4afccfc6cbf3/content/browser/renderer_host/render_widget_host_view_aura.cc
[modify] https://crrev.com/a2b327d0b8e2935ba42f8f4b084c4afccfc6cbf3/content/browser/renderer_host/render_widget_host_view_aura.h
[modify] https://crrev.com/a2b327d0b8e2935ba42f8f4b084c4afccfc6cbf3/content/browser/renderer_host/render_widget_host_view_aura_unittest.cc
[modify] https://crrev.com/a2b327d0b8e2935ba42f8f4b084c4afccfc6cbf3/ui/aura/window.cc
[modify] https://crrev.com/a2b327d0b8e2935ba42f8f4b084c4afccfc6cbf3/ui/views/widget/desktop_aura/desktop_native_widget_aura_unittest.cc
[modify] https://crrev.com/a2b327d0b8e2935ba42f8f4b084c4afccfc6cbf3/ui/views/widget/desktop_aura/desktop_screen_position_client.cc

 Issue 775862  has been merged into this issue.

 Issue 802017  has been merged into this issue.

***UI Mass Triage ***

Seems like WIP and bug is valid, hence tagging with appropriate label.