Predator and CL could not provide any possible suspects.
Using Code Search for the file, "ExecutionContext.cpp" assigning to concern owner.

Suspecting Commit#
https://chromium.googlesource.com/chromium/src/+/0d68a512e634d31dce7d71a71b4c867bf647ccf1

@yukishiino -- Could you please look into the issue, kindly re-assign if this is not related to your changes.
Thank You.

tbansal@, could you take a look?  If you're not one of the right owners of NetworkInformation, could you reroute this issue to the right owners?

At a glance, it seems like that NetworkInformation is accessing an ExecutionContext without checking if it's still available (non-null) or not.

In general, an ExecutionContext can be discarded at some point, so you should check if it's still available or not before its use.

 Issue 756670  has been merged into this issue.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/46e5295e9220f082b0c395b48ded7aea42bb12c7

commit 46e5295e9220f082b0c395b48ded7aea42bb12c7
Author: Tarun Bansal <tbansal@chromium.org>
Date: Fri Aug 18 16:37:57 2017

Check if GetExecutionContext is null in NetInfo API

Bug:  756363 
Change-Id: Idcbdc4e59a311b5ab7bbfd9b67c1eb78f1a661bc
Reviewed-on: https://chromium-review.googlesource.com/620906
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Commit-Queue: Tarun Bansal <tbansal@chromium.org>
Cr-Commit-Position: refs/heads/master@{#495578}
[modify] https://crrev.com/46e5295e9220f082b0c395b48ded7aea42bb12c7/third_party/WebKit/Source/modules/netinfo/NetworkInformation.cpp

ClusterFuzz has detected this issue as fixed in range 495542:495750.

Detailed report: https://clusterfuzz.com/testcase?key=6080292384407552

Fuzzer: lcamtuf_cross_fuzz
Job Type: windows_asan_chrome_no_sandbox
Platform Id: windows

Crash Type: Null-dereference READ
Crash Address: 0x00000000
Crash State:
  blink::ExecutionContext::Url
  blink::NetworkInformation::GetRandomMultiplier
  blink::NetworkInformation::downlink
  
Sanitizer: address (ASAN)

Regressed: https://clusterfuzz.com/revisions?job=windows_asan_chrome_no_sandbox&range=494860:494916
Fixed: https://clusterfuzz.com/revisions?job=windows_asan_chrome_no_sandbox&range=495542:495750

Reproducer Testcase: https://clusterfuzz.com/download?testcase_id=6080292384407552

See https://github.com/google/clusterfuzz-tools for more information.

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

ClusterFuzz testcase 6080292384407552 is verified as fixed, so closing issue as verified.

If this is incorrect, please add ClusterFuzz-Wrong label and re-open the issue.

ClusterFuzz testcase 4698420211351552 is still reproducing on tip-of-tree build (trunk).

Please re-test your fix against this testcase and if the fix was incorrect or incomplete, please re-open the bug. Otherwise, ignore this notification and add ClusterFuzz-Wrong label.