Add ability to handle data from multiple streams in RateAccCounter.

webrtc/video/stats_counter.h

Index: webrtc/video/stats_counter.h
diff --git a/webrtc/video/stats_counter.h b/webrtc/video/stats_counter.h
index c272b6278d0961b69362748ab7272ba5c4b2af71..85acc658ff26e05a4a72bd5b56ead8c7cb38b3ea 100644
--- a/webrtc/video/stats_counter.h
+++ b/webrtc/video/stats_counter.h
@@ -20,6 +20,7 @@ namespace webrtc {
 
 class AggregatedCounter;
 class Clock;
+class Samples;
 
 // |StatsCounterObserver| is called periodically when a metric is updated.
 class StatsCounterObserver {
@@ -88,19 +89,16 @@ class StatsCounter {
                StatsCounterObserver* observer);
 
   void Add(int sample);
-  void Set(int sample);
+  void Set(int sample, uint32_t ssrc);
 
-  int max_;
-  int64_t sum_;
-  int64_t num_samples_;
-  int64_t last_sum_;
+  const std::unique_ptr<Samples> samples_;
+  const bool include_empty_intervals_;
 
  private:
   bool TimeToProcess();
   void TryProcess();
 
   Clock* const clock_;
-  const bool include_empty_intervals_;
   const std::unique_ptr<StatsCounterObserver> observer_;
   const std::unique_ptr<AggregatedCounter> aggregated_counter_;
   int64_t last_process_time_ms_;
@@ -218,7 +216,7 @@ class RateAccCounter : public StatsCounter {
                  bool include_empty_intervals);
   ~RateAccCounter() override {}
 
-  void Set(int sample);
+  void Set(int sample, uint32_t ssrc);
 
  private:
   bool GetMetric(int* metric) const override;