Bug 1348182 - default suspend-background-video to off in media mochitests. r=kaku

There is a bug in this feature which somehow prevents MDSM from reaching the
end of playback and firing the 'ended' event. We will default this feature to
off in media tests and tests for this feature need to turn it on explicitly.

We will also open a new bug to investigate this issue.

MozReview-Commit-ID: 8ebgcHGPKY0

--HG--
extra : rebase_source : f5a7dcf4a80eece6270e2757d7c41e5eaaff60e9

testing/profiles/prefs_general.js

@@ -47,6 +47,7 @@ user_pref("media.cache_size", 1000);
 user_pref("media.volume_scale", "0.01");
 user_pref("media.test.dumpDebugInfo", true);
 user_pref("media.dormant-on-pause-timeout-ms", 0); // Enter dormant immediately without waiting for timeout.
+user_pref("media.suspend-bkgnd-video.enabled", false);
 user_pref("security.warn_viewing_mixed", false);
 user_pref("app.update.enabled", false);
 user_pref("app.update.staging.enabled", false);