Change pre_encode_callback to get a const frame.

webrtc/video/vie_encoder.cc

Index: webrtc/video/vie_encoder.cc
diff --git a/webrtc/video/vie_encoder.cc b/webrtc/video/vie_encoder.cc
index 24b8ce3cd1c4e392d2a0fef1ec8ffb8f00a4050b..1aab37a5e22fb7b258a4829563e17af393625ed2 100644
--- a/webrtc/video/vie_encoder.cc
+++ b/webrtc/video/vie_encoder.cc
@@ -82,7 +82,7 @@ ViEEncoder::ViEEncoder(uint32_t number_of_cores,
                        const std::vector<uint32_t>& ssrcs,
                        ProcessThread* module_process_thread,
                        SendStatisticsProxy* stats_proxy,
-                       I420FrameCallback* pre_encode_callback,
+                       rtc::VideoSinkInterface<VideoFrame>* pre_encode_callback,
                        OveruseFrameDetector* overuse_detector,
                        PacedSender* pacer,
                        PayloadRouter* payload_router)
@@ -343,13 +343,8 @@ void ViEEncoder::EncodeVideoFrame(const VideoFrame& video_frame) {
     }
   }
 
-  // If we haven't resampled the frame and we have a FrameCallback, we need to
-  // make a deep copy of |video_frame|.
-  VideoFrame copied_frame;
   if (pre_encode_callback_) {
-    copied_frame.CopyFrame(*frame_to_send);
-    pre_encode_callback_->FrameCallback(&copied_frame);
-    frame_to_send = &copied_frame;
+    pre_encode_callback_->OnFrame(*frame_to_send);
   }
 
   if (codec_type == webrtc::kVideoCodecVP8) {