After the change, the separator looks like this:

Deleted: Screenshot from 2016-08-26 15:25:28.png 4.3 KB

	Screenshot from 2016-08-26 15:25:28.png 4.3 KB View Download

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/fde074ca9cad340a826f85834e5b942fcd555a8d

commit fde074ca9cad340a826f85834e5b942fcd555a8d
Author: yiyix <yiyix@chromium.org>
Date: Fri Aug 26 20:29:25 2016

Update Tray Separator Opacity

The tray separator has an opacity of 0.24 and it looks too dim when the
shelf is completely opaque. Update the tray separator's opacity to 0.3.

BUG= 641453 

Review-Url: https://codereview.chromium.org/2281173002
Cr-Commit-Position: refs/heads/master@{#414798}

[modify] https://crrev.com/fde074ca9cad340a826f85834e5b942fcd555a8d/ash/common/system/tray/tray_constants.cc

The separator still looks too dim. Update the alpha value to 0.6.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/07bf97af7414cc14268f99055f5f9671e1b9fea2

commit 07bf97af7414cc14268f99055f5f9671e1b9fea2
Author: yiyix <yiyix@chromium.org>
Date: Tue Nov 01 00:10:57 2016

Update Tray Separator Opacity

The tray separator has an opacity of 0.3 and it looks too dim when the
shelf is completely opaque. Update the tray separator's opacity to 0.6.

BUG= 641453 

Review-Url: https://codereview.chromium.org/2470543002
Cr-Commit-Position: refs/heads/master@{#428876}

[modify] https://crrev.com/07bf97af7414cc14268f99055f5f9671e1b9fea2/ash/common/system/tray/tray_constants.cc

Yi, can this be marked as Fixed (did you show Sebastien a screenshot of the separator with the new opacity)?

I have showed the screenshot to Sebastien. We both like the final appearance.