Adding FEC support in NetEq 4.

R=henrik.lundin@webrtc.org, turaj@webrtc.org

TEST=passes all trybots

BUG=

Review URL: https://webrtc-codereview.appspot.com/9999004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@5748 4adac7df-926f-26a2-2b94-8c16560cd09d
diff --git a/webrtc/modules/audio_coding/neteq4/packet_buffer.cc b/webrtc/modules/audio_coding/neteq4/packet_buffer.cc
index c461463..0cc0854 100644
--- a/webrtc/modules/audio_coding/neteq4/packet_buffer.cc
+++ b/webrtc/modules/audio_coding/neteq4/packet_buffer.cc
@@ -238,8 +238,15 @@
     AudioDecoder* decoder =
         decoder_database->GetDecoder(packet->header.payloadType);
     if (decoder) {
-      int duration = packet->sync_packet ? last_duration :
-          decoder->PacketDuration(packet->payload, packet->payload_length);
+      int duration;
+      if (packet->sync_packet) {
+        duration = last_duration;
+      } else {
+        duration = packet->primary ?
+            decoder->PacketDuration(packet->payload, packet->payload_length) :
+            decoder->PacketDurationRedundant(packet->payload,
+                                             packet->payload_length);
+      }
       if (duration >= 0) {
         last_duration = duration;  // Save the most up-to-date (valid) duration.
       }