Make RTCStatsReport::ToString() return JSON-parseable string.

webrtc/stats/rtcstatsreport.cc

Index: webrtc/stats/rtcstatsreport.cc
diff --git a/webrtc/stats/rtcstatsreport.cc b/webrtc/stats/rtcstatsreport.cc
index 566aef8772de09d18103123d8a9a17082e523bac..ca99cef2fa1225540a6948c811c25a5b7996b64c 100644
--- a/webrtc/stats/rtcstatsreport.cc
+++ b/webrtc/stats/rtcstatsreport.cc
@@ -103,14 +103,15 @@ RTCStatsReport::ConstIterator RTCStatsReport::end() const {
                        stats_.cend());
 }
 
-std::string RTCStatsReport::ToString() const {
+std::string RTCStatsReport::ToJson() const {
   std::ostringstream oss;
   ConstIterator it = begin();
   if (it != end()) {
-    oss << it->ToString();
+    oss << '[' << it->ToJson();
     for (++it; it != end(); ++it) {
-      oss << '\n' << it->ToString();
+      oss << ",\n" << it->ToJson();
     }
+    oss << ']';

[hbos, 2017/07/27 16:27:41]

Again, is this parseable by json? Just an array that isn't an element of a
dictionary?

Currently:
[{
  "type": "type"
  "id": "id1",
  "timestamp": 123,
},
{
  "type": "type"
  "id": "id2",
  "timestamp": 123,
}]

As opposed to:
{"stats": [{
  "type": "type"
  "id": "id1",
  "timestamp": 123,
},
{
  "type": "type"
  "id": "id2",
  "timestamp": 123,
}]}

Or perhaps more appropriately since this is a map:
{"id1": {
  "type": "type"
  "id": "id1",
  "timestamp": 123,
},
"id2": {
  "type": "type"
  "id": "id2",
  "timestamp": 123,
}}

(Or variations with other or no indentations.)

[hbos, 2017/07/27 16:29:28]

In any case, we could get rid of any spaces and newline characters to make this
more compact if it's primarily meant for json parsers.

[ehmaldonado_webrtc, 2017/07/28 09:15:43]

Yes, an array is parseable by JSON.
And done. Erased spaces and newline characters

   }
   return oss.str();
 }