Adding decoded_fec_rate to NetEQ Network Statistics.

A statistic is introduced to reflect the actual benefits of Opus FEC. It shows what percentage of samples in the rendered audio come from FEC data.

BUG=3867
R=henrik.lundin@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/34969004

Cr-Commit-Position: refs/heads/master@{#8384}
git-svn-id: http://webrtc.googlecode.com/svn/trunk@8384 4adac7df-926f-26a2-2b94-8c16560cd09d
diff --git a/webrtc/modules/audio_coding/neteq/interface/neteq.h b/webrtc/modules/audio_coding/neteq/interface/neteq.h
index 2c0dbdc..4847213 100644
--- a/webrtc/modules/audio_coding/neteq/interface/neteq.h
+++ b/webrtc/modules/audio_coding/neteq/interface/neteq.h
@@ -38,6 +38,8 @@
                              // expansion (in Q14).
   uint16_t accelerate_rate;  // Fraction of data removed through acceleration
                              // (in Q14).
+  uint16_t secondary_decoded_rate;  // Fraction of data coming from secondary
+                                    // decoding (in Q14).
   int32_t clockdrift_ppm;  // Average clock-drift in parts-per-million
                            // (positive or negative).
   int added_zero_samples;  // Number of zero samples added in "off" mode.