Test:
- That video decode suspends when enabled and delay is reached.
- That video decode doesn't suspend when disabled.
- That video decode doesn't suspend when video finishes before suspend delay.
These tests need to run from content process to observe the suspend
notifications via nsIObserverService, but access to gBrowser is in
chrome process in e10s. Thus, the reason for loading
background_video_chrome.js into chrome process and invoking functions
via async messages.
MozReview-Commit-ID: 2eE97FEUMPu
--HG--
extra : rebase_source : e48cc4dab54648bf0830f59f346a09ab3fb73f6e
Dan Glastonbury