Looks like a regression from a recent CL?
https://chromium.googlesource.com/chromium/src/+/67d53ace23978af7d28d83fade1a09993079085a

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/0e282db620025b8a3e4386e67e0d76d1008c5742

commit 0e282db620025b8a3e4386e67e0d76d1008c5742
Author: gcomanici <gcomanici@chromium.org>
Date: Mon Apr 03 18:07:48 2017

Fix constructor for AutocompleteMatch to initialize |subtype_identifier|

This bug was due to CL https://codereview.chromium.org/2755503002/.

An additional fix is applied to two comments. These were inconsisitent
with the variable names it they were refering to.

BUG= 707537 

Review-Url: https://codereview.chromium.org/2792983002
Cr-Commit-Position: refs/heads/master@{#461470}

[modify] https://crrev.com/0e282db620025b8a3e4386e67e0d76d1008c5742/components/omnibox/browser/autocomplete_match.cc
[modify] https://crrev.com/0e282db620025b8a3e4386e67e0d76d1008c5742/components/omnibox/browser/autocomplete_match.h
[modify] https://crrev.com/0e282db620025b8a3e4386e67e0d76d1008c5742/components/omnibox/browser/search_suggestion_parser.h

ClusterFuzz has detected this issue as fixed in range 461467:461483.

Detailed report: https://clusterfuzz.com/testcase?key=5132640652099584

Fuzzer: meacer_extension_apis
Job Type: linux_msan_chrome
Platform Id: linux

Crash Type: Use-of-uninitialized-value
Crash Address: 
Crash State:
  OmniboxMetricsProvider::RecordOmniboxOpenedURL
  OmniboxEventGlobalTracker::OnURLOpened
  OmniboxEditModel::OpenMatch
  
Sanitizer: memory (MSAN)

Recommended Security Severity: Low

Regressed: https://clusterfuzz.com/revisions?job=linux_msan_chrome&range=461326:461327
Fixed: https://clusterfuzz.com/revisions?job=linux_msan_chrome&range=461467:461483

Reproducer Testcase: https://clusterfuzz.com/download/AMIfv977hBiUs5anaKV2ucEYnrpF-cGtABWeAWa3yByc6gq1a4B4mN2GOd79UlZyB62A20ENN0ewDur4WFfkN11HRGvHi8va_jMdZJ2a-vUANvFI3A74vfg5KY1p0FJp2nkcUU4UYRu6xPaUSha6fqHHpnWKDL3SBaC_r5wTE8v7JdKpWR3s5EuvZT59IG2yLawRfrTuBg7wbhXDwca3tiCyYf8Dp7ZE84nhkEKLt6Tc2Xjjoe8NWNW_zhtOPs3c1YfNSn1yBzCuvKqyYj1yQeXKWgN1YG0Iiz1UexxSJD_WccSr0T8fj69UMR4fJicRk-rI1pgHMK9u59LvmBq8SQYc1rkxd2_eVyCp6kwXgDrceSKsVPnJPoKE00andq-xdPNhfbtJ0IXFrc6oS7iwqV5UdNGuNi9Xow?testcase_id=5132640652099584


Additional requirements: Requires Gestures

See https://dev.chromium.org/Home/chromium-security/bugs/reproducing-clusterfuzz-bugs for more information.

If you suspect that the result above is incorrect, try re-doing that job on the test case report page.

This bug has been closed for more than 14 weeks. Removing security view restrictions.

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot