Re-comitting r5711: "Fixing a flaky test in video_engine_tests"
Re-comitting r5711: "Fixing a flaky test in video_engine_tests"

The CL was reverted in r5712, due to bots going red. However, these bots
are unrelated to this CL.

Original description:
VideoSendStreamTest.SuspendBelowMinBitrate was flaky. The problem was
that when the first non-padding packet was sent after the stream was
resumed, the statistics had not always been updated so that
stats.suspended was false. After seeing the first non-padding packet
after suspension, the test will now go into a state where it waits for
the statistics to be changed.

BUG=3068
R=pbos@webrtc.org
TBR=stefan@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/10099004

Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: ed8b2812659786106cd70592ed84f9f6475aaa7e

sippet/webrtc,sippet/webrtc,sippet/webrtc,sippet/webrtc,sippet/webrtc,sippet/webrtc