Update I420Buffer to new VideoFrameBuffer interface

webrtc/examples/peerconnection/client/linux/main_wnd.cc

Index: webrtc/examples/peerconnection/client/linux/main_wnd.cc
diff --git a/webrtc/examples/peerconnection/client/linux/main_wnd.cc b/webrtc/examples/peerconnection/client/linux/main_wnd.cc
index 55a59aea2cb8682d154433510bb849d6cbd58287..7a61549e2897cd474a53eb74bde9edf54b48c300 100644
--- a/webrtc/examples/peerconnection/client/linux/main_wnd.cc
+++ b/webrtc/examples/peerconnection/client/linux/main_wnd.cc
@@ -523,8 +523,8 @@ void GtkMainWnd::VideoRenderer::OnFrame(
     const webrtc::VideoFrame& video_frame) {
   gdk_threads_enter();
 
-  rtc::scoped_refptr<webrtc::VideoFrameBuffer> buffer(
-      video_frame.video_frame_buffer());
+  rtc::scoped_refptr<webrtc::PlanarYuvBuffer> buffer(
+      video_frame.video_frame_buffer()->ToI420());
   if (video_frame.rotation() != webrtc::kVideoRotation_0) {
     buffer = webrtc::I420Buffer::Rotate(*buffer, video_frame.rotation());
   }