Add WebrtcVideoEncoder interface

remoting/codec/video_encoder_verbatim.cc

Index: remoting/codec/video_encoder_verbatim.cc
diff --git a/remoting/codec/video_encoder_verbatim.cc b/remoting/codec/video_encoder_verbatim.cc
index 6e01304e3a2ea3ed532ef123df57a989f823dbe2..7dc8e024d1452c8145fa345519db19bda13617e1 100644
--- a/remoting/codec/video_encoder_verbatim.cc
+++ b/remoting/codec/video_encoder_verbatim.cc
@@ -27,8 +27,7 @@ VideoEncoderVerbatim::VideoEncoderVerbatim() {}
 VideoEncoderVerbatim::~VideoEncoderVerbatim() {}
 
 std::unique_ptr<VideoPacket> VideoEncoderVerbatim::Encode(
-    const webrtc::DesktopFrame& frame,
-    uint32_t flags) {
+    const webrtc::DesktopFrame& frame) {
   DCHECK(frame.data());
 
   // If nothing has changed in the frame then return NULL to indicate that