First failing build: https://ci.chromium.org/buildbot/chromium.webkit/WebKit%20Linux%20Trusty%20MSAN/8128

Suspect r564186, which modifies third_party/blink/renderer/modules/webaudio/wave_shaper*.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/db982853616d0152e7d3490ce81171f547839965

commit db982853616d0152e7d3490ce81171f547839965
Author: Matt Giuca <mgiuca@chromium.org>
Date: Tue Jun 05 03:48:19 2018

Revert "WaveShaper must output non-zero values even if input is silent"

This reverts commit 325b492fe733ba4c8b2128069a0a232fea1789e3.

Reason for revert: Broke webaudio/.../waveshaper-364379.html in
webkit_layout_tests. See  https://crbug.com/849535 

Original change's description:
> WaveShaper must output non-zero values even if input is silent
> 
> If the curve for the WaveShaperNode is such that a zero input produces
> a non-zero output, the WaveShaperNode needs to output that value even
> if the input is silent (or disconnected).
> 
> Do this by setting the tail time of the processor to 0 or infinity
> depending on whether the curve specifies an output value of zero or
> not, respectively.
> 
> Bug: 807301
> Test: WaveShaper/silent-inputs.html
> Change-Id: I6539d2e00f5d3e624ffaf2810944eb6d53d6f84b
> Reviewed-on: https://chromium-review.googlesource.com/896266
> Commit-Queue: Raymond Toy <rtoy@chromium.org>
> Reviewed-by: Hongchan Choi <hongchan@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#564186}

TBR=rtoy@chromium.org,hongchan@chromium.org

Change-Id: I29fd96b1a9dd2b87db12867031399b069beba706
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 807301,  849535 
Reviewed-on: https://chromium-review.googlesource.com/1086647
Reviewed-by: Matt Giuca <mgiuca@chromium.org>
Commit-Queue: Matt Giuca <mgiuca@chromium.org>
Cr-Commit-Position: refs/heads/master@{#564359}
[delete] https://crrev.com/8afa16fbeed700655df3e2dcd5f83175b0a415f3/third_party/WebKit/LayoutTests/external/wpt/webaudio/the-audio-api/the-waveshapernode-interface/silent-inputs.html
[modify] https://crrev.com/db982853616d0152e7d3490ce81171f547839965/third_party/blink/renderer/modules/webaudio/wave_shaper_dsp_kernel.cc
[modify] https://crrev.com/db982853616d0152e7d3490ce81171f547839965/third_party/blink/renderer/modules/webaudio/wave_shaper_dsp_kernel.h
[modify] https://crrev.com/db982853616d0152e7d3490ce81171f547839965/third_party/blink/renderer/modules/webaudio/wave_shaper_processor.cc

I'm unable to reproduce with a local MSAN build.  But since the backtrace points to a call to PropagatesSilence() which calls TailTime() for the WaveShaperDSPKernel, which returns tail_time_, I'm guessing the uninitialized variable is tail_time_.  And indeed the constructor doesn't initialize it and depends on SetCurve() to set it.

Removing this from sheriff queue, as there seems to be an unrelated failure on the same builder.