Assigning to the concern from Find it. Below is the find it result --
The result is a list of CLs that change the crashed files. 

Author: lukasza
Project: chromium
Changelist: https://chromium.googlesource.com/chromium/src/+/9d858647530db2c22e1267e443034d23f2e602d9
Time: Thu Dec 08 21:52:12 2016
Lines 74 of file RealtimeAnalyser.cpp which potentially caused crash are changed in this cl (frame #0, "blink::RealtimeAnalyser::setFftSize").
Minimum distance from crash line to modified line: 0. (file: RealtimeAnalyser.cpp, crashed on: 74, modified: 74).

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

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/8c22c74f1f57853ea427fa5f21f170144d4103ed

commit 8c22c74f1f57853ea427fa5f21f170144d4103ed
Author: rtoy <rtoy@chromium.org>
Date: Mon Dec 19 22:58:25 2016

Test for power of two safely

Use integer operations to test if an integer is a power of two.  And
check that the value is in range before testing for a power.

BUG= 675570 
TEST=

Review-Url: https://codereview.chromium.org/2582323003
Cr-Commit-Position: refs/heads/master@{#439603}

[modify] https://crrev.com/8c22c74f1f57853ea427fa5f21f170144d4103ed/third_party/WebKit/Source/modules/webaudio/RealtimeAnalyser.cpp
[modify] https://crrev.com/8c22c74f1f57853ea427fa5f21f170144d4103ed/third_party/WebKit/Source/platform/audio/AudioUtilities.cpp
[modify] https://crrev.com/8c22c74f1f57853ea427fa5f21f170144d4103ed/third_party/WebKit/Source/platform/audio/AudioUtilities.h

ClusterFuzz has detected this issue as fixed in range 439552:439637.

Detailed report: https://cluster-fuzz.appspot.com/testcase?key=6302487985520640

Fuzzer: inferno_twister
Job Type: linux_ubsan_chrome
Platform Id: linux

Crash Type: Float-cast-overflow
Crash Address: 
Crash State:
  blink::RealtimeAnalyser::setFftSize
  blink::AnalyserHandler::setFftSize
  fftSizeAttributeSetter
  
Regressed: https://cluster-fuzz.appspot.com/revisions?job=linux_ubsan_chrome&range=435261:438085
Fixed: https://cluster-fuzz.appspot.com/revisions?job=linux_ubsan_chrome&range=439552:439637

Minimized Testcase (0.20 Kb):
Download: https://cluster-fuzz.appspot.com/download/AMIfv96m894FLwdU0RYOHzDWN74TdCGkX3EQn66bUyCNAQCES4_QcZOWT2n0C0PudC8fi2SX_LG81TOoTPE2qwfjZ8sEjQ85tkvstrMhZSxrcHVCZnJ_tnhiO0QOtjGRbET98Z02vQis3y8_mCjSEvgn4xXYa_jvGw?testcase_id=6302487985520640
<script>
var Context1= new (window.webkitOfflineAudioContext || window.OfflineAudioContext)(32,231706,44100)
var Analyser3=Context1.createAnalyser();
{;
}
{;
}
Analyser3.fftSize=-0.5146401333622634;
</script>


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.

ClusterFuzz testcase 6302487985520640 is verified as fixed, so closing issue.

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