Suspect the following patch causes this flakiness:
https://chromium-review.googlesource.com/c/chromium/src/+/1371071

Since the flakiness is observed on only chromium.memory/Linux CFI bot, I will disable PasswordManagerBrowserTest.DeleteFrameBeforeSubmit on Linux CFI bot.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/aa5a3d4bffe1d611e2e77178624371d8f2b0a12f

commit aa5a3d4bffe1d611e2e77178624371d8f2b0a12f
Author: Takashi Sakamoto <tasak@google.com>
Date: Wed Dec 19 08:31:49 2018

[Sheriff] Mark PasswordManagerTest.DeleteFrameBeforeSubmit as flaky on chromium.memory/Linux CFI

TBR=thestig@chromium.org

Bug: 916413
Change-Id: If53c96e162c8369c01565a4d01657d705e412207
Reviewed-on: https://chromium-review.googlesource.com/c/1383758
Reviewed-by: Takashi Sakamoto <tasak@google.com>
Commit-Queue: Takashi Sakamoto <tasak@google.com>
Cr-Commit-Position: refs/heads/master@{#617769}
[modify] https://crrev.com/aa5a3d4bffe1d611e2e77178624371d8f2b0a12f/chrome/browser/password_manager/password_manager_browsertest.cc

 Issue 916441  has been merged into this issue.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/a33861d819ceef401231fd6b8ce37e9a36d1d159

commit a33861d819ceef401231fd6b8ce37e9a36d1d159
Author: Takashi Sakamoto <tasak@google.com>
Date: Wed Dec 19 10:20:20 2018

Revert "[Sheriff] Mark PasswordManagerTest.DeleteFrameBeforeSubmit as flaky on chromium.memory/Linux CFI"

This reverts commit aa5a3d4bffe1d611e2e77178624371d8f2b0a12f.

Reason for revert: Re-enable PasswordManagerTest.DeleteFrameBeforeSubmit test to revert r617657.

Original change's description:
> [Sheriff] Mark PasswordManagerTest.DeleteFrameBeforeSubmit as flaky on chromium.memory/Linux CFI
> 
> TBR=thestig@chromium.org
> 
> Bug: 916413
> Change-Id: If53c96e162c8369c01565a4d01657d705e412207
> Reviewed-on: https://chromium-review.googlesource.com/c/1383758
> Reviewed-by: Takashi Sakamoto <tasak@google.com>
> Commit-Queue: Takashi Sakamoto <tasak@google.com>
> Cr-Commit-Position: refs/heads/master@{#617769}

TBR=tasak@google.com

Change-Id: Ifcdda3eea33de9e289c771cd167c3227cb36796a
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 916413
Reviewed-on: https://chromium-review.googlesource.com/c/1383762
Reviewed-by: Takashi Sakamoto <tasak@google.com>
Commit-Queue: Takashi Sakamoto <tasak@google.com>
Cr-Commit-Position: refs/heads/master@{#617783}
[modify] https://crrev.com/a33861d819ceef401231fd6b8ce37e9a36d1d159/chrome/browser/password_manager/password_manager_browsertest.cc

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/8953b6f7ba5eb917a5d75d5571b128586b5a4be8

commit 8953b6f7ba5eb917a5d75d5571b128586b5a4be8
Author: Lutz Justen <ljusten@chromium.org>
Date: Wed Dec 19 10:22:19 2018

[Sheriff] Revert "Skip NavigationScheduler for form submission"

This reverts commit d86b336f22131fdd8d65e57cd09178ae26ababa4.

Reason for revert: Probably responsible for flakiness in PasswordManagerBrowserTest.DeleteFrameBeforeSubmit test.

BUG=chromium:916413

Original change's description:
> Skip NavigationScheduler for form submission
> 
> Bug: 914587
> Change-Id: I272044a02e9180defd7201198a5909d4ea302eb6
> Reviewed-on: https://chromium-review.googlesource.com/c/1371071
> Commit-Queue: Nate Chapin <japhet@chromium.org>
> Reviewed-by: Dmitry Gozman <dgozman@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#617657}

TBR=dgozman@chromium.org,dcheng@chromium.org,japhet@chromium.org

Change-Id: Ib50d642d3df7e8e87c06a618c5f32a4ebc6641ee
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 914587
Reviewed-on: https://chromium-review.googlesource.com/c/1384065
Reviewed-by: Lutz Justen <ljusten@chromium.org>
Commit-Queue: Lutz Justen <ljusten@chromium.org>
Cr-Commit-Position: refs/heads/master@{#617784}
[modify] https://crrev.com/8953b6f7ba5eb917a5d75d5571b128586b5a4be8/third_party/blink/renderer/core/frame/frame.h
[modify] https://crrev.com/8953b6f7ba5eb917a5d75d5571b128586b5a4be8/third_party/blink/renderer/core/frame/local_frame.cc
[modify] https://crrev.com/8953b6f7ba5eb917a5d75d5571b128586b5a4be8/third_party/blink/renderer/core/frame/local_frame.h
[modify] https://crrev.com/8953b6f7ba5eb917a5d75d5571b128586b5a4be8/third_party/blink/renderer/core/frame/remote_frame.cc
[modify] https://crrev.com/8953b6f7ba5eb917a5d75d5571b128586b5a4be8/third_party/blink/renderer/core/frame/remote_frame.h
[modify] https://crrev.com/8953b6f7ba5eb917a5d75d5571b128586b5a4be8/third_party/blink/renderer/core/html/forms/html_form_element.cc
[modify] https://crrev.com/8953b6f7ba5eb917a5d75d5571b128586b5a4be8/third_party/blink/renderer/core/loader/navigation_scheduler.cc
[modify] https://crrev.com/8953b6f7ba5eb917a5d75d5571b128586b5a4be8/third_party/blink/renderer/core/loader/navigation_scheduler.h
[modify] https://crrev.com/8953b6f7ba5eb917a5d75d5571b128586b5a4be8/third_party/blink/web_tests/dom/legacy_dom_conformance/xhtml/level2/html/HTMLFormElement10.js
[modify] https://crrev.com/8953b6f7ba5eb917a5d75d5571b128586b5a4be8/third_party/blink/web_tests/fast/events/popup-blocked-to-post-blank-expected.txt
[modify] https://crrev.com/8953b6f7ba5eb917a5d75d5571b128586b5a4be8/third_party/blink/web_tests/fast/forms/form-submission-create-crash.xhtml
[modify] https://crrev.com/8953b6f7ba5eb917a5d75d5571b128586b5a4be8/third_party/blink/web_tests/fast/forms/select/select-empty-optgroup-crash.html
[modify] https://crrev.com/8953b6f7ba5eb917a5d75d5571b128586b5a4be8/third_party/blink/web_tests/fast/forms/submit-add-remove-element.html
[modify] https://crrev.com/8953b6f7ba5eb917a5d75d5571b128586b5a4be8/third_party/blink/web_tests/http/tests/loading/307-after-303-after-post-expected.txt
[modify] https://crrev.com/8953b6f7ba5eb917a5d75d5571b128586b5a4be8/third_party/blink/web_tests/http/tests/loading/redirect-methods-expected.txt
[modify] https://crrev.com/8953b6f7ba5eb917a5d75d5571b128586b5a4be8/third_party/blink/web_tests/http/tests/security/contentSecurityPolicy/1.1/form-action-src-get-blocked-with-redirect-expected.txt
[modify] https://crrev.com/8953b6f7ba5eb917a5d75d5571b128586b5a4be8/third_party/blink/web_tests/http/tests/security/contentSecurityPolicy/1.1/form-action-src-redirect-blocked-expected.txt
[modify] https://crrev.com/8953b6f7ba5eb917a5d75d5571b128586b5a4be8/third_party/blink/web_tests/virtual/mouseevent_fractional/fast/events/popup-blocked-to-post-blank-expected.txt
[modify] https://crrev.com/8953b6f7ba5eb917a5d75d5571b128586b5a4be8/third_party/blink/web_tests/virtual/user-activation-v2/fast/events/popup-blocked-to-post-blank-expected.txt

For flakiness see
https://findit-for-me.appspot.com/waterfall/flake/flake-culprit?key=ag9zfmZpbmRpdC1mb3ItbWVyQwsSDEZsYWtlQ3VscHJpdCIxY2hyb21pdW0vZDg2YjMzNmYyMjEzMWZkZDhkNjVlNTdjZDA5MTc4YWUyNmFiYWJhNAw