Add encoding time and and fps to webrtc.stress case.

tools/perf/benchmarks/webrtc.py

Index: tools/perf/benchmarks/webrtc.py
diff --git a/tools/perf/benchmarks/webrtc.py b/tools/perf/benchmarks/webrtc.py
index 2f781edd39650a45fa3452bc71508ac284d74c84..d9388a7fc052b8310042dc0b517bd7ad7bbd3412 100644
--- a/tools/perf/benchmarks/webrtc.py
+++ b/tools/perf/benchmarks/webrtc.py
@@ -60,7 +60,9 @@ class WebrtcStressTest(perf_benchmark.PerfBenchmark):
     return 'webrtc.stress'
 
   def CreatePageTest(self, options):
-    return webrtc.WebRTC(use_webrtc_stats=False)
+    # Exclude all stats.
+    return webrtc.WebRTC(particular_metrics=['googAvgEncodeMs',
+                                             'googFrameRateReceived'])
 
 
 # WebrtcRendering must be a PerfBenchmark, and not a _Webrtc, because it is a