Restore mixing integration tests.

These high level tests were disabled over time. Since they depend on
real-time results and the filesystem, they tended to be flaky on the
bots. We now give it a very generous 1 second to start up all channels
before verification and a further relaxed file length check. If we
continue to see problems, I will up the startup delay.

The restored tests would have caught the AGC bug fixed here:
https://code.google.com/p/webrtc/source/detail?r=5454

Add a new "real audio" stress test to exercise more code paths. This
would have caught the refactor bug fixed here:
https://code.google.com/p/webrtc/source/detail?r=5437

BUG=2164,2844
TESTED=git try. Verified it would have caught the aforementioned bugs
by reintroducing them.

R=andresp@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/8009004

git-svn-id: http://webrtc.googlecode.com/svn/trunk/webrtc@5522 4adac7df-926f-26a2-2b94-8c16560cd09d
1 file changed