UserAgent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/49.0.2623.87 Safari/537.36

Example URL:
https://soundcloud.com/eric

Steps to reproduce the problem:
This does not happen reliably, however there have been several reports from different users of Chrome 49/Mac.

1. Open a page on soundcloud.com which has many waveforms (these are rendered in <canvas>)
2. Switch to a different tab.
3. Switch back to the SoundCloud tab

What is the expected behavior?
The page should appear as it was the first time, with waveforms showing.

What went wrong?
The waveforms are missing.

Does it occur on multiple sites: N/A

Is it a problem with a plugin? N/A 

Did this work before? Yes First reports came in from users on Chrome 49

Does this work in other browsers? Yes 

Chrome version: 49.0.2623.87  Channel: stable
OS Version: 10.10.5 (Yosemite)
Flash Version: Shockwave Flash 21.0 r0

Switching tabs again (to a different tab, then back to SoundCloud) solves the problem.

This may or may not be related to #595063 and #588434