Get VideoCapturer stats via VideoTrackSourceInterface in StatsCollector,

webrtc/api/rtpsenderinterface.h

Index: webrtc/api/rtpsenderinterface.h
diff --git a/webrtc/api/rtpsenderinterface.h b/webrtc/api/rtpsenderinterface.h
index 776d01ace6b4457a960dbcf1795d70e8de11c805..09de1d1637502bb54c65b232d794bf27335dc9c4 100644
--- a/webrtc/api/rtpsenderinterface.h
+++ b/webrtc/api/rtpsenderinterface.h
@@ -19,6 +19,7 @@
 #include "webrtc/api/mediastreaminterface.h"
 #include "webrtc/api/proxy.h"
 #include "webrtc/api/rtpparameters.h"
+#include "webrtc/api/statstypes.h"
 #include "webrtc/base/refcount.h"
 #include "webrtc/base/scoped_ref_ptr.h"
 #include "webrtc/pc/mediasession.h"
@@ -55,6 +56,10 @@ class RtpSenderInterface : public rtc::RefCountInterface {
   virtual RtpParameters GetParameters() const = 0;
   virtual bool SetParameters(const RtpParameters& parameters) = 0;
 
+  // Returns a scoped_refptr(nullptr) if there are no stats.

[perkj_webrtc, 2016/03/29 11:03:39]

? StatsReport::Id is a scoped_refptr?  

[nisse-webrtc, 2016/03/29 11:37:31]

Yes, defined in statstypes.h as

  typedef rtc::scoped_refptr<IdBase> Id;

+  virtual StatsReport::Id stats_id() = 0;
+  virtual void ReportStats(StatsReport* report) = 0;

[perkj_webrtc, 2016/03/29 11:03:39]

Prefer GetStats anyway (saw your comments) since its widely used in the code
base for stats. 

[nisse-webrtc, 2016/03/29 11:37:31]

Most other GetStats methods either take an observer, or they work with a plain
struct. But I'll rename it if you really want.

I think StatsReport is a too opaque type to be used for anything not directly
tied to StatsCollector. E.g., if you write test cases related to the stats for
some component, it's going to be annoying and error prone to have to access the
produced stats via StatsReport::FindValue(StatsReport::kSomething).int_val(),
not to speak about error checking needed if you want the testcase to report the
precise problem rather than crash.

[tommi, 2016/03/30 11:46:45]

Is this method's implementation expected to block at any time?  If so, should it
be designed to be async? (as GetStats is)

[nisse-webrtc, 2016/03/30 12:09:31]

It shouldn't block. If the RtpSender is connected to a camera, it ends up in
cricket::VideoCapturer::GetStats which returns the size of the most recent
captured frame (after taking the frame_stats_crit_ lock, which only competes
with UpdateStats). In all other cases, it does nothing.

+
  protected:
   virtual ~RtpSenderInterface() {}
 };
@@ -72,6 +77,8 @@ PROXY_CONSTMETHOD0(std::string, stream_id)
 PROXY_METHOD0(void, Stop)
 PROXY_CONSTMETHOD0(RtpParameters, GetParameters);
 PROXY_METHOD1(bool, SetParameters, const RtpParameters&)
+PROXY_METHOD0(StatsReport::Id, stats_id)
+PROXY_METHOD1(void, ReportStats, StatsReport*)

[tommi, 2016/03/30 11:46:45]

as is, all proxy methods involve a synchronous thread hop.  This is unfortunate
and I'd like for us to design the APIs with more asynchronicity in mind.

 END_PROXY()
 
 }  // namespace webrtc