Refactor rtcp statistics: Rtcp module take narrow interface

webrtc/modules/rtp_rtcp/include/receive_statistics.h

Index: webrtc/modules/rtp_rtcp/include/receive_statistics.h
diff --git a/webrtc/modules/rtp_rtcp/include/receive_statistics.h b/webrtc/modules/rtp_rtcp/include/receive_statistics.h
index 90a848ad6335bd7584a67e013b2d7e7c7a7d820f..e77e7a9f23a93975c6e4e8a427d8cb3aa0233606 100644
--- a/webrtc/modules/rtp_rtcp/include/receive_statistics.h
+++ b/webrtc/modules/rtp_rtcp/include/receive_statistics.h
@@ -12,15 +12,27 @@
 #define WEBRTC_MODULES_RTP_RTCP_INCLUDE_RECEIVE_STATISTICS_H_
 
 #include <map>
+#include <vector>
 
 #include "webrtc/modules/include/module.h"
 #include "webrtc/modules/include/module_common_types.h"
+#include "webrtc/modules/rtp_rtcp/source/rtcp_packet/report_block.h"
 #include "webrtc/typedefs.h"
 
 namespace webrtc {
 
 class Clock;
 
+class ReceiveStatisticsReporter {
+ public:
+  // Fill in statistic fields of the rtcp report blocks for the active ssrcs.
+  // (i.e. everything except last_sr/delay_since_last_sr fields)
+  virtual std::vector<rtcp::ReportBlock> GetActiveStatistics() = 0;
+
+ protected:
+  ~ReceiveStatisticsReporter() = default;
+};
+
 class StreamStatistician {
  public:
   virtual ~StreamStatistician();
@@ -46,7 +58,7 @@ class StreamStatistician {
 
 typedef std::map<uint32_t, StreamStatistician*> StatisticianMap;
 
-class ReceiveStatistics {
+class ReceiveStatistics : public ReceiveStatisticsReporter {
  public:
   virtual ~ReceiveStatistics() {}
 
@@ -78,6 +90,9 @@ class ReceiveStatistics {
   // Called on new RTP stats creation.
   virtual void RegisterRtpStatisticsCallback(
       StreamDataCountersCallback* callback) = 0;
+
+  // TODO(danilchap): Remove other accessors and make this one pure virtual.
+  std::vector<rtcp::ReportBlock> GetActiveStatistics() override;
 };
 
 class NullReceiveStatistics : public ReceiveStatistics {