UserAgent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_10_5) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/49.0.2623.87 Safari/537.36

Example URL:

Steps to reproduce the problem:
1. I am using pdf.js(customised to our app) to load pdf
2. switch to another tab which is play youtube video
3. switch back and find canvas is blank but it will be ok if I switch to another tab and switch back again
4. If I disable software acceleration, the problem seems gone

What is the expected behavior?

What went wrong?
See steps to reproduce the problem

Does it occur on multiple sites: N/A

Is it a problem with a plugin? N/A 

Did this work before? N/A 

Does this work in other browsers? N/A 

Chrome version: 49.0.2623.87  Channel: n/a
OS Version: OS X 10.10.5
Flash Version: Shockwave Flash 21.0 r0