The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/10eebe4810ba48d961183f8405a6f1404274142c

commit 10eebe4810ba48d961183f8405a6f1404274142c
Author: Joshua Bell <jsbell@chromium.org>
Date: Wed Mar 21 21:03:05 2018

Skip LayoutTests/external/wpt/webaudio/idlharness.https.html on MSAN

Like the corresponding DOM and SVG idlharness tests, the (new)
WebAudio comprehensive IDLHarness test is just too slow on the MSAN
bots and times out. Since it's unlikely we'll fix it and we don't
want to slow down the builds, [Skip] it.

Bug:  824455 
Change-Id: Ie8b5f34edeccfa87f4385de0b2797871c48db35f
Reviewed-on: https://chromium-review.googlesource.com/973985
Reviewed-by: Thomas Guilbert <tguilbert@chromium.org>
Commit-Queue: Joshua Bell <jsbell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#544839}
[modify] https://crrev.com/10eebe4810ba48d961183f8405a6f1404274142c/third_party/WebKit/LayoutTests/MSANExpectations

Fixed? 

Or maybe we should mark as [Slow] and see if that's sufficient? I don't want to make the *SAN bots flaky while we experiment, though. :(

The first build to have the fix has not yet finished running:
https://uberchromegw.corp.google.com/i/chromium.webkit/builders/WebKit%20Linux%20Trusty%20MSAN/builds/6730