Merge to 57: Screen content simulcast layers should not be downscaled.

Merge to 57: Screen content simulcast layers should not be downscaled.

Fix config so, size isn't downscaled, add unit test coverage.

BUG=webrtc:7171, webrtc:4172
Original Review-Url: https://codereview.webrtc.org/2692343007
Original Cr-Commit-Position: refs/heads/master@{#16648}

R=mflodman@webrtc.org

Review-Url: https://codereview.webrtc.org/2709733002 .
Cr-Commit-Position: refs/branch-heads/57@{#6}
Cr-Branched-From: e5cbc2019003dbb40e03811d7607feb95757a4ec-refs/heads/master@{#16123}
Committed: https://chromium.googlesource.com/external/webrtc/+/0a71dc836641acdaaa63b2724f83c822dbb58ce7

[sprang_webrtc, 2017-02-21 13:08:17]

sprang@webrtc.org changed reviewers:
+ mflodman@webrtc.org

[mflodman, 2017-02-21 14:09:30]

lgtm

[sprang_webrtc, 2017-02-21 14:18:21]

Description was changed from

==========
Merge to 57: Screen content simulcast layers should not be downscaled.

Fix config so, size isn't downscaled, add unit test coverage.

BUG=webrtc:7171, webrtc:4172

Original Review-Url: https://codereview.webrtc.org/2692343007
Original Cr-Commit-Position: refs/heads/master@{#16648}
==========

to

==========
Merge to 57: Screen content simulcast layers should not be downscaled.

Fix config so, size isn't downscaled, add unit test coverage.

BUG=webrtc:7171, webrtc:4172

Original Review-Url: https://codereview.webrtc.org/2692343007
Original Cr-Commit-Position: refs/heads/master@{#16648}

R=mflodman@webrtc.org

Review-Url: https://codereview.webrtc.org/2709733002 .
Cr-Commit-Position: refs/branch-heads/57@{#6}
Cr-Branched-From:
e5cbc2019003dbb40e03811d7607feb95757a4ec-refs/heads/master@{#16123}
Committed:
https://chromium.googlesource.com/external/webrtc/+/0a71dc836641acdaaa63b2724...
==========

[sprang_webrtc, 2017-02-21 14:18:23]

Committed patchset #1 (id:1) manually as
0a71dc836641acdaaa63b2724f83c822dbb58ce7 (presubmit successful).