After https://codereview.webrtc.org/2386573002 changed where resolution
changes are handled, a few VideoSendStreamTests became flaky. They were
waiting for an InitEncode call they triggered, but sometimes were
getting one triggered by the resolution change when the first frame was
generated.
The fix was to make the tests wait for two InitEncode calls first -
one when the stream is created, and the second when the first frame was
encoded.
BUG=webrtc:6467, webrtc:6371
R=perkj@webrtc.org, stefan@webrtc.org
Review URL: https://codereview.webrtc.org/2387293002 .
Cr-Commit-Position: refs/heads/master@{#14490}
cf33d9c9d3