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 c6e6151933ea53fe88afb085c4fd0c158888ed46..08663f80155f1a6c582015e49e899e5550fa75eb 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 {
@@ -104,15 +105,12 @@ class StatsCounter {
                StatsCounterObserver* observer);
 
   void Add(int sample);
-  void Set(int sample);
+  void Set(int sample, uint32_t stream_id);
 
-  int max_;
-  int64_t sum_;
-  int64_t num_samples_;
-  int64_t last_sum_;
-
-  const std::unique_ptr<AggregatedCounter> aggregated_counter_;
+  const bool include_empty_intervals_;
   const int64_t process_intervals_ms_;
+  const std::unique_ptr<AggregatedCounter> aggregated_counter_;
+  const std::unique_ptr<Samples> samples_;
 
  private:
   bool TimeToProcess(int* num_elapsed_intervals);
@@ -121,7 +119,6 @@ class StatsCounter {
   bool IncludeEmptyIntervals() const;
 
   Clock* const clock_;
-  const bool include_empty_intervals_;
   const std::unique_ptr<StatsCounterObserver> observer_;
   int64_t last_process_time_ms_;
   bool paused_;
@@ -262,7 +259,7 @@ class RateAccCounter : public StatsCounter {
                  bool include_empty_intervals);
   ~RateAccCounter() override {}
 
-  void Set(int sample);
+  void Set(int sample, uint32_t stream_id);
 
  private:
   bool GetMetric(int* metric) const override;