api: fix non-compliant timestamp field in stats

It must be a (double) number, expressed in milliseconds. The native API
provides microseconds though.

Author: saghul

android/src/main/java/com/oney/WebRTCModule/StringUtils.java

@@ -35,9 +35,9 @@ public static String statsToJSON(RTCStatsReport report) {
 
             RTCStats stats = statsMap.get(key);
             builder
-                .append("\"timestamp\":\"")
-                .append(stats.getTimestampUs())
-                .append("\",\"type\":\"")
+                .append("\"timestamp\":")
+                .append(stats.getTimestampUs() / 1000.0)
+                .append(",\"type\":\"")
                 .append(stats.getType())
                 .append("\",\"id\":\"")
                 .append(stats.getId())

ios/RCTWebRTC/WebRTCModule+RTCPeerConnection.m

@@ -339,9 +339,9 @@ - (NSString *)statsToJSON:(RTCStatisticsReport *)report
     [s appendString:@"\",{"];
 
     RTCStatistics *statistics = report.statistics[key];
-    [s appendString:@"\"timestamp\":\""];
-    [s appendFormat:@"%f", statistics.timestamp_us];
-    [s appendString:@"\",\"type\":\""]; 
+    [s appendString:@"\"timestamp\":"];
+    [s appendFormat:@"%f", statistics.timestamp_us / 1000.0];
+    [s appendString:@",\"type\":\""]; 
     [s appendString:statistics.type];
     [s appendString:@"\",\"id\":\""];
     [s appendString:statistics.id];