Remove ViEImageProcess usage in VideoSendStream.
Remove ViEImageProcess usage in VideoSendStream.

Replaces interface usage with direct calls on ViEEncoder removing a
layer of indirection. Also removing some methods from ViEImageProcess
that were only added for Video{Send,Receive}Stream usage.

BUG=1695
R=stefan@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/45319004

Cr-Original-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#9111}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: 94cc1fe4af57a01a99a1f76f0ad3d48edf981321

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