The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/48b791c315ea56c1cd29a01283e466afd3dc4f08

commit 48b791c315ea56c1cd29a01283e466afd3dc4f08
Author: rtoy <rtoy@chromium.org>
Date: Mon Feb 06 22:39:30 2017

Convert GainNode tests to testharness

Manually converted the tests to use testharness.

Also modified gain.html not to create an audio file.  Instead, we load
up the reference output and compare against the output of the gain
node.  Test passes if the individual samples are close enough and the
SNR is high enough.

BUG= 688169 
TEST=gain-basic.html, gain.html

Review-Url: https://codereview.chromium.org/2671883002
Cr-Commit-Position: refs/heads/master@{#448418}

[delete] https://crrev.com/05bcaa3b45a4c51d157608db31a367b09553471c/third_party/WebKit/LayoutTests/webaudio/Gain/gain-basic-expected.txt
[modify] https://crrev.com/48b791c315ea56c1cd29a01283e466afd3dc4f08/third_party/WebKit/LayoutTests/webaudio/Gain/gain-basic.html
[modify] https://crrev.com/48b791c315ea56c1cd29a01283e466afd3dc4f08/third_party/WebKit/LayoutTests/webaudio/Gain/gain.html