WebRtcStatsPerfBrowserTest added, a perf test using the new getStats

chrome/browser/media/webrtc/webrtc_browsertest_base.h

Index: chrome/browser/media/webrtc/webrtc_browsertest_base.h
diff --git a/chrome/browser/media/webrtc/webrtc_browsertest_base.h b/chrome/browser/media/webrtc/webrtc_browsertest_base.h
index eb7c45c57b33a0444e2ff687a1d1aa00dcacb988..826e17d6f9248756526c2cffe56b67c48d3895a5 100644
--- a/chrome/browser/media/webrtc/webrtc_browsertest_base.h
+++ b/chrome/browser/media/webrtc/webrtc_browsertest_base.h
@@ -43,6 +43,7 @@ class WebRtcTestBase : public InProcessBrowserTest {
   static const char kFailedWithPermissionDismissedError[];
 
   static const char kUseDefaultCertKeygen[];
+  static const char kUseDefaultAudioCodec[];
   static const char kUseDefaultVideoCodec[];
 
  protected:
@@ -174,7 +175,9 @@ class WebRtcTestBase : public InProcessBrowserTest {
   std::vector<std::string> GetWhitelistedStatsTypes(
       content::WebContents* tab) const;
 
-  // Change the default video codec in the offer SDP.
+  // Change the default audio/video codec in the offer SDP.
+  void SetDefaultAudioCodec(content::WebContents* tab,
+                            const std::string& audio_codec) const;
   void SetDefaultVideoCodec(content::WebContents* tab,
                             const std::string& video_codec) const;