So, you had typed "http:/" when it crashed?

I think I had typed part of the URL, and then backspace to delete some parts of it. It's a bit hard to repro :(
One thing I know for sure is that it crashes while the user is typing (i.e., before I typed enter or selected anything from the autocomplete options that show up).

manukh: Please take a look and see if you can figure out under what circumstances where this might happen. If you have any questions about how these code paths work, I can walk you through it offline.

seems these steps reliably reproduce the issue:

1. navigate to `google.com`
2. focus the omnibox, it should now say `https://www.google.com`
3. delete the ending `google.com` so that the remaining text is `https://www.`

regarding step 3:

- deleting by backspacing 1-char-at-a-time causes the issue.

- selecting the last 10 characters and pressing backspace/delete once also reproduces the issue.

- selecting the last 11 characters `.google.com` and deleting does not cause the issue.

typing in `https://www.` and then deleting the inline autocompletion (press delete once) also reproduces the crash

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/61d1146d76ddba79ed29fa8ad368494f930cca2d

commit 61d1146d76ddba79ed29fa8ad368494f930cca2d
Author: manuk <manukh@chromium.org>
Date: Tue Oct 30 21:11:14 2018

[Omnibox] Use GURL::possibly_invalid_spec instead of GURL::spec when sorting and deduping matches.

Certain omnibox inputs, such as `http:www.` produce matches with invalid urls. Invoking GURL::spec on these invalid GURL's caused a DCHECK to evaluate false and crash the browser. The crash only affects debug builds as the DCHECK is inactive for non-debug builds.

Bug:  898554 
Change-Id: I89a27f902b77bf6b221c321ab396787e9249a4e6
Reviewed-on: https://chromium-review.googlesource.com/c/1308260
Commit-Queue: manuk hovanesian <manukh@chromium.org>
Reviewed-by: Tommy Li <tommycli@chromium.org>
Cr-Commit-Position: refs/heads/master@{#604012}
[modify] https://crrev.com/61d1146d76ddba79ed29fa8ad368494f930cca2d/components/omnibox/browser/autocomplete_result.cc

Can you look closer at what part of the system is generating URLs with invalid specs?  This probably shouldn't be happening (not even for the what-you-typed URL suggestion), and it's probably indication of an underlying bug.

I agree.  I think the CL should be reverted.  Left a more detailed comment on the review.

Worth noting, as far as I can tell, this (not checking url validity) was the past behavior (before Aug 24), so it's possible whatever is causing invalid urls has existed a long time.

I will look into it.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/b5b111f70b97a3a60c14d1c45845a1f12a9da0ad

commit b5b111f70b97a3a60c14d1c45845a1f12a9da0ad
Author: manuk hovanesian <manukh@chromium.org>
Date: Thu Nov 01 16:21:48 2018

Revert "[Omnibox] Use GURL::possibly_invalid_spec instead of GURL::spec when sorting and deduping matches."

This reverts commit 61d1146d76ddba79ed29fa8ad368494f930cca2d.

Reason for revert: per review comments, there may be a larger underlying reason as to why we we're generating invalid GURL's that should be addressed.

Original change's description:
> [Omnibox] Use GURL::possibly_invalid_spec instead of GURL::spec when sorting and deduping matches.
> 
> Certain omnibox inputs, such as `http:www.` produce matches with invalid urls. Invoking GURL::spec on these invalid GURL's caused a DCHECK to evaluate false and crash the browser. The crash only affects debug builds as the DCHECK is inactive for non-debug builds.
> 
> Bug:  898554 
> Change-Id: I89a27f902b77bf6b221c321ab396787e9249a4e6
> Reviewed-on: https://chromium-review.googlesource.com/c/1308260
> Commit-Queue: manuk hovanesian <manukh@chromium.org>
> Reviewed-by: Tommy Li <tommycli@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#604012}

TBR=krb@chromium.org,tommycli@chromium.org,manukh@chromium.org

Change-Id: I3e2dddb8dd218bce805dc93d842f83b7366cf1bb
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug:  898554 
Reviewed-on: https://chromium-review.googlesource.com/c/1308603
Reviewed-by: Tommy Li <tommycli@chromium.org>
Commit-Queue: manuk hovanesian <manukh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#604610}
[modify] https://crrev.com/b5b111f70b97a3a60c14d1c45845a1f12a9da0ad/components/omnibox/browser/autocomplete_result.cc

Triggering the omnibox input `https://www.` after a deletion (e.g. typing in `https://www.x` then pressing backspace) so that inline autocomplete is prevented results in a url-what-you-typed match from the HistoryURL provider with the valid url `https://www./`. For de-duping purposes, we attempt to remove the host `www.` and get the url `https:/`, which is invalid.

Maybe someone more familiar knows if, or what part of, the above behavior is expected or should be changed?

Removing the "www." for deduping is invalid when that leaves no host components.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/7c10eab1d69f3cdbc406917f0de0209ba36b0d63

commit 7c10eab1d69f3cdbc406917f0de0209ba36b0d63
Author: manuk <manukh@chromium.org>
Date: Tue Nov 13 19:50:07 2018

[Omnibox] Avoid removing the `www.` prefix during deduping when doing so would leave no host component.

When sorting and deduping matches, match GURLs are stripped (`AutocompleteMatch::GURLToStrippedGURL`). Certain omnibox inputs, such as `http://www.` without inline autocomplete, produce matches with host compoments `www.`. Stripping `www.` in these cases would result in an empty url host component and, therefore, invalid `GURL`. Invoking `GURL::spec` on such invalid URLs would then cause a DCHECK to evaluate false and crash the browser. The crash only affects debug builds as the DCHECK is inactive for non-debug builds.

Bug:  898554 
Change-Id: I73461c65ba53891d6f3b52bc767c754b02c1ce3e
Reviewed-on: https://chromium-review.googlesource.com/c/1331631
Commit-Queue: manuk hovanesian <manukh@chromium.org>
Reviewed-by: Tommy Li <tommycli@chromium.org>
Cr-Commit-Position: refs/heads/master@{#607709}
[modify] https://crrev.com/7c10eab1d69f3cdbc406917f0de0209ba36b0d63/components/omnibox/browser/autocomplete_match.cc
[modify] https://crrev.com/7c10eab1d69f3cdbc406917f0de0209ba36b0d63/components/omnibox/browser/autocomplete_match_unittest.cc