Don't treat picture ids as wrapping in the FrameBuffer2 class.

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 f314ccb5f6461f3c05a17ff4f2873ab9e942a163..5b81c5f997bb833f13067eb080c4237b2b77bfe9 100644
--- a/webrtc/modules/video_coding/frame_buffer2.cc
+++ b/webrtc/modules/video_coding/frame_buffer2.cc
@@ -248,9 +248,13 @@ void FrameBuffer::Stop() {
 }
 
 bool FrameBuffer::ValidReferences(const FrameObject& frame) const {
+  if (frame.picture_id < 0)

[terelius, 2017/09/11 16:10:22]

What does it mean if we get frame with negative picure_id? Can this even happen?

+    return false;
+
   for (size_t i = 0; i < frame.num_references; ++i) {
-    if (AheadOrAt<uint16_t>(frame.references[i], frame.picture_id))
+    if (frame.references[i] < 0 || 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])
         return false;