Fix problem with late packets in NetEq

Since r7255, it could happen that an old packet would block the decoding
process until enough packet was received for the buffer to flush. This
CL fixes that by:
- Partially reverting r7255;
- Remove recent old packets before taking a decision for GetAudio;
- Remove all old packets after a packet has been extracted for decoding;
- Adding tests for reordered packets.

BUG=chrome:423985
R=tina.legrand@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/25079004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@7612 4adac7df-926f-26a2-2b94-8c16560cd09d

webrtc/modules/audio_coding/neteq/neteq_impl.cc

@@ -868,6 +868,10 @@ int NetEqImpl::GetDecision(Operations* operation,
 
   assert(sync_buffer_.get());
   uint32_t end_timestamp = sync_buffer_->end_timestamp();
+  if (!new_codec_) {
+    const uint32_t five_seconds_samples = 5 * fs_hz_;
+    packet_buffer_->DiscardOldPackets(end_timestamp, five_seconds_samples);
+  }
   const RTPHeader* header = packet_buffer_->NextRtpHeader();
 
   if (decision_logic_->CngRfc3389On() || last_mode_ == kModeRfc3389Cng) {
@@ -884,7 +888,7 @@ int NetEqImpl::GetDecision(Operations* operation,
       }
       // Check buffer again.
       if (!new_codec_) {
-        packet_buffer_->DiscardOldPackets(end_timestamp);
+        packet_buffer_->DiscardOldPackets(end_timestamp, 5 * fs_hz_);
       }
       header = packet_buffer_->NextRtpHeader();
     }
@@ -1823,7 +1827,7 @@ int NetEqImpl::ExtractPackets(int required_samples, PacketList* packet_list) {
     // we could end up in the situation where we never decode anything, since
     // all incoming packets are considered too old but the buffer will also
     // never be flooded and flushed.
-    packet_buffer_->DiscardOldPackets(timestamp_);
+    packet_buffer_->DiscardAllOldPackets(timestamp_);
   }
 
   return extracted_samples;