Unwrap picture ids in the RtpFrameReferencerFinder.

webrtc/modules/video_coding/frame_buffer2.cc

Index: webrtc/modules/video_coding/frame_buffer2.cc
diff --git a/webrtc/modules/video_coding/frame_buffer2.cc b/webrtc/modules/video_coding/frame_buffer2.cc
index 7fcb728ae411ff5afeeb127b51a9f28f00dc3ccf..f314ccb5f6461f3c05a17ff4f2873ab9e942a163 100644
--- a/webrtc/modules/video_coding/frame_buffer2.cc
+++ b/webrtc/modules/video_coding/frame_buffer2.cc
@@ -249,7 +249,7 @@ void FrameBuffer::Stop() {
 
 bool FrameBuffer::ValidReferences(const FrameObject& frame) const {
   for (size_t i = 0; i < frame.num_references; ++i) {
-    if (AheadOrAt(frame.references[i], frame.picture_id))
+    if (AheadOrAt<uint16_t>(frame.references[i], frame.picture_id))
       return false;
     for (size_t j = i + 1; j < frame.num_references; ++j) {
       if (frame.references[i] == frame.references[j])