This is true of our current implementation, only the shadows are 0.5 pt so the "blobs" are less noticeable. I don't have a good solution in mind for mitigating this as long as we are drawing tab backgrounds with assets. Assigning to me to come up with a fix for.

One possible approach is for tabs below the first in a "stack" to not have shadows at all.

The approach we took in desktop Chrome to avoid this was to clip stacked tabs against the next tab's outline path.

pkasting's described implementation sounds nice but we wont be able to get an outline path considering our tab shapes are assets (Mark, correct me if I'm wrong).

Mark I think your proposal in #2 is reasonable but I worry it would be hard to coordinate when scrolling? IDK, I will leave that to you and Justin to discuss. Assign back to me if you need anything (like a shadowless variant of the background tab shapes??).

 Issue 843308  has been merged into this issue.

Per offline conversation with pschaffner@, lets update the asset for now.

We used to do this even with assets in desktop -- we manually draw a path we knew matched the asset.  Then you have to keep them updated in sync, which is a pain.  Of course the long term solution is probably programmatic drawing.

Attached are new assets (also available here: https://drive.google.com/open?id=14d53aIrYInQVH7oG_itP3ye6ooeNp1SL&authuser=pschaffner@google.com) that use the same hairline shadow as our previous tabs. This is a stopgap solution seeing as larger tab strip work is in the pipeline.

Deleted: Tab Strip Backgrounds.zip 33.6 KB

Tab Strip Backgrounds.zip 33.6 KB Download

Here is a mock showing ~what it will look like.

Deleted: Apple iPad Air 2 Silver@2x.png 408 KB

	Apple iPad Air 2 Silver@2x.png 408 KB View Download

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/b85ebef528e90732357572883382623e19442223

commit b85ebef528e90732357572883382623e19442223
Author: Justin Cohen <justincohen@google.com>
Date: Wed May 30 15:16:59 2018

[ios] Update tab strip tab art for refresh.

Removes shadows around refresh artwork, and all the necessary pixel tweakage.

screenshot: https://screenshot.googleplex.com/pawpDoFFzVY

Bug:  844006 
Cq-Include-Trybots: luci.chromium.try:ios-simulator-full-configs;master.tryserver.chromium.mac:ios-simulator-cronet
Change-Id: I760902a0820b0426d75d571163cdc2ab7c7782a4
Reviewed-on: https://chromium-review.googlesource.com/1078912
Reviewed-by: Rohit Rao <rohitrao@chromium.org>
Commit-Queue: Justin Cohen <justincohen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#562828}
[modify] https://crrev.com/b85ebef528e90732357572883382623e19442223/ios/chrome/browser/ui/tabs/resources/tabstrip_background_tab.imageset/tabstrip_background_tab@2x~ipad.png
[modify] https://crrev.com/b85ebef528e90732357572883382623e19442223/ios/chrome/browser/ui/tabs/resources/tabstrip_background_tab.imageset/tabstrip_background_tab~ipad.png
[modify] https://crrev.com/b85ebef528e90732357572883382623e19442223/ios/chrome/browser/ui/tabs/resources/tabstrip_foreground_tab.imageset/tabstrip_foreground_tab@2x~ipad.png
[modify] https://crrev.com/b85ebef528e90732357572883382623e19442223/ios/chrome/browser/ui/tabs/resources/tabstrip_foreground_tab.imageset/tabstrip_foreground_tab~ipad.png
[modify] https://crrev.com/b85ebef528e90732357572883382623e19442223/ios/chrome/browser/ui/tabs/resources/tabstrip_incognito_background_tab.imageset/tabstrip_incognito_background_tab@2x~ipad.png
[modify] https://crrev.com/b85ebef528e90732357572883382623e19442223/ios/chrome/browser/ui/tabs/resources/tabstrip_incognito_background_tab.imageset/tabstrip_incognito_background_tab~ipad.png
[modify] https://crrev.com/b85ebef528e90732357572883382623e19442223/ios/chrome/browser/ui/tabs/resources/tabstrip_incognito_foreground_tab.imageset/tabstrip_incognito_foreground_tab@2x~ipad.png
[modify] https://crrev.com/b85ebef528e90732357572883382623e19442223/ios/chrome/browser/ui/tabs/resources/tabstrip_incognito_foreground_tab.imageset/tabstrip_incognito_foreground_tab~ipad.png
[modify] https://crrev.com/b85ebef528e90732357572883382623e19442223/ios/chrome/browser/ui/tabs/tab_strip_controller.mm
[modify] https://crrev.com/b85ebef528e90732357572883382623e19442223/ios/chrome/browser/ui/tabs/tab_view.mm

Verified in 69.0.3449.0 Canary, iPad Air  iOS11.4

Shadow is not shown.