Change unit of logged bitrate stats in bytes/s to bits/s.

Multiplier added to ToString method in AggregatedStats.

BUG=webrtc:5283

Review-Url: https://codereview.webrtc.org/2535323003
Cr-Commit-Position: refs/heads/master@{#15330}
diff --git a/webrtc/video/stats_counter.cc b/webrtc/video/stats_counter.cc
index b1c24ee..86dedd9 100644
--- a/webrtc/video/stats_counter.cc
+++ b/webrtc/video/stats_counter.cc
@@ -26,11 +26,15 @@
 }  // namespace
 
 std::string AggregatedStats::ToString() const {
+  return ToStringWithMultiplier(1);
+}
+
+std::string AggregatedStats::ToStringWithMultiplier(int multiplier) const {
   std::stringstream ss;
   ss << "periodic_samples:" << num_samples << ", {";
-  ss << "min:" << min << ", ";
-  ss << "avg:" << average << ", ";
-  ss << "max:" << max << "}";
+  ss << "min:" << (min * multiplier) << ", ";
+  ss << "avg:" << (average * multiplier) << ", ";
+  ss << "max:" << (max * multiplier) << "}";
   return ss.str();
 }