It turns out this is not an issue specifically related to iOS 11, but EarlGrey's bug, I 'll check back some time later to see if it's fixed.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/eacf11a106f04ac5c871c32b879aef1453451d7d

commit eacf11a106f04ac5c871c32b879aef1453451d7d
Author: Yuke Liao <liaoyuke@chromium.org>
Date: Fri Aug 04 23:14:20 2017

Fix testDeletionInDetailView on iPhone 6 Plus.

This test is trying to tap on the delete button in the password detail
view and then tap delete confirmation button to confirm. This test
fails on iPhone 6 Plus because the matcher mistakenly matches both the
delete confirmation button and the hidden delete button in the password
detail view.

Apparently, EarlGrey should be able to differentiate those two button
by sufficiently visibility, but fails to do so. I've talked to the
EarlGrey team, they think there is a bug that's causing the failure
and they will take a look when they have time, but unfortunately, it 
wont be a high priority thing for them.

While waiting for EarlGrey team to dig deeper, I'm implementing this
hack to fix the failure for now, and will revisit once I hear back from
EarlGrey team.

Bug: 751311
Change-Id: I6e61f6c3d1ef2e100a407f55b259938865c7ff05
Reviewed-on: https://chromium-review.googlesource.com/596726
Commit-Queue: Yuke Liao <liaoyuke@chromium.org>
Reviewed-by: Justin Cohen <justincohen@chromium.org>
Reviewed-by: Rohit Rao (ping after 24h) <rohitrao@chromium.org>
Cr-Commit-Position: refs/heads/master@{#492166}
[modify] https://crrev.com/eacf11a106f04ac5c871c32b879aef1453451d7d/ios/chrome/browser/ui/settings/passwords_settings_egtest.mm

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/09f852a1086fd3ad4314ab0d03ff38fccc309aa5

commit 09f852a1086fd3ad4314ab0d03ff38fccc309aa5
Author: Yi Su <mrsuyi@chromium.org>
Date: Thu Nov 29 12:31:49 2018

Migrate PasswordDetailsCollectionViewController from
CollectionViewController to ChromeTableViewController.

This CL migrates the PasswordDetailsCollectionViewController from
CollectionViewController, which is based on MDCCollectionViewController,
to ChromeTableViewController, which is based on UITableViewController.

Bug: 894791,751311
Change-Id: I3f76e28c1e42720d4d316b2a9018c01313646fbb
Reviewed-on: https://chromium-review.googlesource.com/c/1346951
Reviewed-by: Eric Noyau <noyau@chromium.org>
Reviewed-by: Gauthier Ambard <gambard@chromium.org>
Commit-Queue: Yi Su <mrsuyi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#612162}
[modify] https://crrev.com/09f852a1086fd3ad4314ab0d03ff38fccc309aa5/ios/chrome/browser/ui/settings/BUILD.gn
[delete] https://crrev.com/6461382f9332d4c3302c5ead5b1d97df2e288b89/ios/chrome/browser/ui/settings/password_details_collection_view_controller.h
[delete] https://crrev.com/6461382f9332d4c3302c5ead5b1d97df2e288b89/ios/chrome/browser/ui/settings/password_details_collection_view_controller_delegate.h
[delete] https://crrev.com/6461382f9332d4c3302c5ead5b1d97df2e288b89/ios/chrome/browser/ui/settings/password_details_collection_view_controller_for_testing.h
[delete] https://crrev.com/6461382f9332d4c3302c5ead5b1d97df2e288b89/ios/chrome/browser/ui/settings/password_details_collection_view_controller_unittest.mm
[add] https://crrev.com/09f852a1086fd3ad4314ab0d03ff38fccc309aa5/ios/chrome/browser/ui/settings/password_details_table_view_controller+testing.h
[add] https://crrev.com/09f852a1086fd3ad4314ab0d03ff38fccc309aa5/ios/chrome/browser/ui/settings/password_details_table_view_controller.h
[rename] https://crrev.com/09f852a1086fd3ad4314ab0d03ff38fccc309aa5/ios/chrome/browser/ui/settings/password_details_table_view_controller.mm
[add] https://crrev.com/09f852a1086fd3ad4314ab0d03ff38fccc309aa5/ios/chrome/browser/ui/settings/password_details_table_view_controller_delegate.h
[add] https://crrev.com/09f852a1086fd3ad4314ab0d03ff38fccc309aa5/ios/chrome/browser/ui/settings/password_details_table_view_controller_unittest.mm
[modify] https://crrev.com/09f852a1086fd3ad4314ab0d03ff38fccc309aa5/ios/chrome/browser/ui/settings/passwords_settings_egtest.mm
[modify] https://crrev.com/09f852a1086fd3ad4314ab0d03ff38fccc309aa5/ios/chrome/browser/ui/settings/save_passwords_collection_view_controller.h
[modify] https://crrev.com/09f852a1086fd3ad4314ab0d03ff38fccc309aa5/ios/chrome/browser/ui/settings/save_passwords_collection_view_controller.mm
[modify] https://crrev.com/09f852a1086fd3ad4314ab0d03ff38fccc309aa5/ios/chrome/browser/ui/settings/save_passwords_collection_view_controller_unittest.mm
[modify] https://crrev.com/09f852a1086fd3ad4314ab0d03ff38fccc309aa5/ios/chrome/browser/ui/table_view/cells/table_view_cells_constants.h
[modify] https://crrev.com/09f852a1086fd3ad4314ab0d03ff38fccc309aa5/ios/chrome/browser/ui/table_view/cells/table_view_text_header_footer_item.mm
[modify] https://crrev.com/09f852a1086fd3ad4314ab0d03ff38fccc309aa5/ios/chrome/browser/ui/table_view/cells/table_view_text_item.mm
[modify] https://crrev.com/09f852a1086fd3ad4314ab0d03ff38fccc309aa5/ios/chrome/browser/ui/table_view/chrome_table_view_controller_test.mm
[modify] https://crrev.com/09f852a1086fd3ad4314ab0d03ff38fccc309aa5/ios/chrome/test/app/password_test_util.mm

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/1bf6ef7848e79f9503fc7a812aa6f0e065c7555f

commit 1bf6ef7848e79f9503fc7a812aa6f0e065c7555f
Author: Yi Su <mrsuyi@chromium.org>
Date: Wed Dec 12 12:21:33 2018

Migrate SavePasswordsCollectionViewController.

This CL migrates the SavePasswordsCollectionViewController from
CollectionViewController, which is based on MDCCollectionViewController,
to ChromeTableViewController, which is based on UITableViewController.

old version UI:
https://drive.google.com/open?id=1wep_qWxpoFYed6K3k2y2uwN6nJZut5f3
https://drive.google.com/open?id=1n_Vzc5AjlnrmAL5BmaGEuY18kG_3DKL4
https://drive.google.com/open?id=1G3ceF52yDQcg2WDvthP7dIPCy-BND_w1

new version UI:
https://drive.google.com/open?id=1HC33oWDWtgd0V1daf7OYceUo7zj5dB8t
https://drive.google.com/open?id=1P7wi_a47hpWzzB30nzIV9JIu1puwGL8r
https://drive.google.com/open?id=1E1EYLq56jsy9QjSkzqcPTUCdV0XBkeS1

Bug: 894791,751311
Change-Id: I7ae4b244a9eb18d0c4af556ae2ed39da4fec0451
Reviewed-on: https://chromium-review.googlesource.com/c/1361241
Reviewed-by: Eric Noyau <noyau@chromium.org>
Reviewed-by: Sergio Collazos <sczs@chromium.org>
Reviewed-by: Chris Lu <thegreenfrog@chromium.org>
Commit-Queue: Yi Su <mrsuyi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#615861}
[modify] https://crrev.com/1bf6ef7848e79f9503fc7a812aa6f0e065c7555f/ios/chrome/browser/ui/autofill/manual_fill/BUILD.gn
[modify] https://crrev.com/1bf6ef7848e79f9503fc7a812aa6f0e065c7555f/ios/chrome/browser/ui/autofill/manual_fill/password_view_controller_egtest.mm
[modify] https://crrev.com/1bf6ef7848e79f9503fc7a812aa6f0e065c7555f/ios/chrome/browser/ui/settings/BUILD.gn
[modify] https://crrev.com/1bf6ef7848e79f9503fc7a812aa6f0e065c7555f/ios/chrome/browser/ui/settings/cells/settings_search_item.h
[modify] https://crrev.com/1bf6ef7848e79f9503fc7a812aa6f0e065c7555f/ios/chrome/browser/ui/settings/cells/settings_search_item.mm
[modify] https://crrev.com/1bf6ef7848e79f9503fc7a812aa6f0e065c7555f/ios/chrome/browser/ui/settings/password_details_table_view_controller.mm
[modify] https://crrev.com/1bf6ef7848e79f9503fc7a812aa6f0e065c7555f/ios/chrome/browser/ui/settings/passwords_settings_egtest.mm
[add] https://crrev.com/1bf6ef7848e79f9503fc7a812aa6f0e065c7555f/ios/chrome/browser/ui/settings/passwords_table_view_controller.h
[rename] https://crrev.com/1bf6ef7848e79f9503fc7a812aa6f0e065c7555f/ios/chrome/browser/ui/settings/passwords_table_view_controller.mm
[add] https://crrev.com/1bf6ef7848e79f9503fc7a812aa6f0e065c7555f/ios/chrome/browser/ui/settings/passwords_table_view_controller_unittest.mm
[delete] https://crrev.com/9aa69dc23c484b7364f446e0acebbb32f0f3e3f7/ios/chrome/browser/ui/settings/save_passwords_collection_view_controller.h
[delete] https://crrev.com/9aa69dc23c484b7364f446e0acebbb32f0f3e3f7/ios/chrome/browser/ui/settings/save_passwords_collection_view_controller_unittest.mm
[modify] https://crrev.com/1bf6ef7848e79f9503fc7a812aa6f0e065c7555f/ios/chrome/browser/ui/settings/settings_collection_view_controller.mm
[modify] https://crrev.com/1bf6ef7848e79f9503fc7a812aa6f0e065c7555f/ios/chrome/browser/ui/settings/settings_navigation_controller.mm
[modify] https://crrev.com/1bf6ef7848e79f9503fc7a812aa6f0e065c7555f/ios/chrome/browser/ui/settings/settings_root_table_view_controller.h
[modify] https://crrev.com/1bf6ef7848e79f9503fc7a812aa6f0e065c7555f/ios/chrome/browser/ui/settings/settings_root_table_view_controller.mm
[modify] https://crrev.com/1bf6ef7848e79f9503fc7a812aa6f0e065c7555f/ios/chrome/browser/ui/table_view/cells/table_view_cells_constants.h
[modify] https://crrev.com/1bf6ef7848e79f9503fc7a812aa6f0e065c7555f/ios/chrome/test/app/password_test_util.mm