RTC[In/Out]boundRTPStreamStats: qpSum,framesDecoded,framesEncoded added.

Recently added to the spec:
RTCRTPStreamStats.qpSum - https://w3c.github.io/webrtc-stats/#dom-rtcrtpstreamstats-qpsum
RTCInboundRTPStreamStats.framesDecoded - https://w3c.github.io/webrtc-stats/#dom-rtcinboundrtpstreamstats-framesdecoded
RTCOutboundRTPStreamStats.framesEncoded - https://w3c.github.io/webrtc-stats/#dom-rtcoutboundrtpstreamstats-framesencoded

These are added and collected. However, the qpSum is only collected in
the outbound case. It should be collected in the inbound case before
closing crbug.com/657855

BUG=chromium:657854, chromium:657855, chromium:657856

Review-Url: https://codereview.webrtc.org/2588373005
Cr-Commit-Position: refs/heads/master@{#15872}
diff --git a/webrtc/api/rtcstatscollector.cc b/webrtc/api/rtcstatscollector.cc
index 4e5e8d9..ff7b751 100644
--- a/webrtc/api/rtcstatscollector.cc
+++ b/webrtc/api/rtcstatscollector.cc
@@ -198,6 +198,7 @@
       static_cast<uint32_t>(video_receiver_info.plis_sent);
   inbound_video->nack_count =
       static_cast<uint32_t>(video_receiver_info.nacks_sent);
+  inbound_video->frames_decoded = video_receiver_info.frames_decoded;
 }
 
 // Provides the media independent counters (both audio and video).
@@ -242,6 +243,9 @@
       static_cast<uint32_t>(video_sender_info.plis_rcvd);
   outbound_video->nack_count =
       static_cast<uint32_t>(video_sender_info.nacks_rcvd);
+  if (video_sender_info.qp_sum)
+    outbound_video->qp_sum = *video_sender_info.qp_sum;
+  outbound_video->frames_encoded = video_sender_info.frames_encoded;
 }
 
 void ProduceCertificateStatsFromSSLCertificateStats(