Add some unit tests to TestVp8Impl.

BUG=webrtc:6634

Review-Url: https://codereview.webrtc.org/3005533003
Cr-Original-Commit-Position: refs/heads/master@{#19623}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: f2972ba1665557fdec5691622c92c0aef869e0f1
1 file changed