Add periodic logging of video stats.

webrtc/media/engine/webrtcvideoengine2.h

Index: webrtc/media/engine/webrtcvideoengine2.h
diff --git a/webrtc/media/engine/webrtcvideoengine2.h b/webrtc/media/engine/webrtcvideoengine2.h
index 14f271f1df65aa843154c56b5e778d13c5773748..e0e3971e56cbbe94a214998907f12d9cb82b03a0 100644
--- a/webrtc/media/engine/webrtcvideoengine2.h
+++ b/webrtc/media/engine/webrtcvideoengine2.h
@@ -377,6 +377,7 @@ class WebRtcVideoChannel2 : public VideoMediaChannel, public webrtc::Transport {
     // Total number of times resolution as been requested to be changed due to
     // CPU adaptation.
     int number_of_cpu_adapt_changes_;
+    int64_t last_stats_log_ms_;
     rtc::VideoSourceInterface<cricket::VideoFrame>* source_;
     WebRtcVideoEncoderFactory* const external_encoder_factory_
         GUARDED_BY(lock_);
@@ -486,6 +487,8 @@ class WebRtcVideoChannel2 : public VideoMediaChannel, public webrtc::Transport {
     WebRtcVideoDecoderFactory* const external_decoder_factory_;
     std::vector<AllocatedDecoder> allocated_decoders_;
 
+    int64_t last_stats_log_ms_;
+
     rtc::CriticalSection sink_lock_;
     rtc::VideoSinkInterface<cricket::VideoFrame>* sink_ GUARDED_BY(sink_lock_);
     int last_width_ GUARDED_BY(sink_lock_);
@@ -553,6 +556,7 @@ class WebRtcVideoChannel2 : public VideoMediaChannel, public webrtc::Transport {
   VideoOptions default_send_options_;
   VideoRecvParameters recv_params_;
   bool red_disabled_by_remote_side_;
+  int64_t last_stats_log_ms_;
 };
 
 }  // namespace cricket