RTCIceCandidateStats.deleted = false added.

Since previously, only the deleted = false case is supported, but now
that stat is added. It's a recent addition to the spec:
https://w3c.github.io/webrtc-stats/#dom-rtcicecandidatestats-deleted

BUG=webrtc:6756, chromium:632723, chromium:627816

Review-Url: https://codereview.webrtc.org/2591963003
Cr-Commit-Position: refs/heads/master@{#15871}
diff --git a/webrtc/stats/rtcstats_objects.cc b/webrtc/stats/rtcstats_objects.cc
index 487df93..966c845 100644
--- a/webrtc/stats/rtcstats_objects.cc
+++ b/webrtc/stats/rtcstats_objects.cc
@@ -242,7 +242,8 @@
     &protocol,
     &candidate_type,
     &priority,
-    &url);
+    &url,
+    &deleted);
 
 RTCIceCandidateStats::RTCIceCandidateStats(
     const std::string& id, int64_t timestamp_us, bool is_remote)
@@ -258,7 +259,8 @@
       protocol("protocol"),
       candidate_type("candidateType"),
       priority("priority"),
-      url("url") {
+      url("url"),
+      deleted("deleted", false) {
 }
 
 RTCIceCandidateStats::RTCIceCandidateStats(const RTCIceCandidateStats& other)
@@ -269,7 +271,8 @@
       protocol(other.protocol),
       candidate_type(other.candidate_type),
       priority(other.priority),
-      url(other.url) {
+      url(other.url),
+      deleted(other.deleted) {
 }
 
 RTCIceCandidateStats::~RTCIceCandidateStats() {