Add network quality change events to net log

net/log/net_log_event_type_list.h

Index: net/log/net_log_event_type_list.h
diff --git a/net/log/net_log_event_type_list.h b/net/log/net_log_event_type_list.h
index e7b4227fb47b5592a70d2afde2ca4d820923227c..9f0b1ffc95257a633803575df1b4b79627c14b71 100644
--- a/net/log/net_log_event_type_list.h
+++ b/net/log/net_log_event_type_list.h
@@ -3040,3 +3040,19 @@ EVENT_TYPE(UPLOAD_DATA_STREAM_READ)
 //   "trigger": <Trigger for evaluation that caused request start>
 // }
 EVENT_TYPE(RESOURCE_SCHEDULER_REQUEST_STARTED)
+
+// -----------------------------------------------------------------------------
+// Network Quality Estimator related events
+// -----------------------------------------------------------------------------
+
+// This event is emitted whenever NetworkQualityEstimator determines that the
+// quality of the network has changed.

[bengr, 2017/01/11 22:13:22]

How often can this happen? We shouldn't spam net log.

[tbansal1, 2017/01/11 23:25:38]

ECT does not change too often. Also, NQE uses net log with source, so at any
time there is at most one NQE entry in the net-internals. In the worst case,
only that entry will get spammed will multiple events.

+// parameters:
+//  {
+//    "http_rtt": <Current estimate of the HTTP RTT>,
+//    "transport_rtt": <Current estimate of the transport RTT>,
+//    "downstream_throughput": <Current estimate of the downstream throughput>,
+//    "effective_connection_type": <Current estimate of the effective connection
+//                                  type>,
+//  }
+EVENT_TYPE(NETWORK_QUALITY_CHANGED)