Expose packet loss counts from QUIC to NetworkQualityEstimator

net/base/socket_performance_watcher_factory.h

Index: net/base/socket_performance_watcher_factory.h
diff --git a/net/base/socket_performance_watcher_factory.h b/net/base/socket_performance_watcher_factory.h
index cbd607ab3366cbba1e24dea1a6dcaab205dd8320..5e9e30e7dec627e1304545ed0dbeca71f803404e 100644
--- a/net/base/socket_performance_watcher_factory.h
+++ b/net/base/socket_performance_watcher_factory.h
@@ -5,6 +5,8 @@
 #ifndef NET_BASE_SOCKET_PERFORMANCE_WATCHER_FACTORY_H_
 #define NET_BASE_SOCKET_PERFORMANCE_WATCHER_FACTORY_H_
 
+#include <stdint.h>
+
 #include "base/macros.h"
 #include "base/memory/scoped_ptr.h"
 #include "net/base/net_export.h"
@@ -42,6 +44,37 @@ class NET_EXPORT_PRIVATE SocketPerformanceWatcherFactory {
   virtual void OnUpdatedRTTAvailable(const Protocol protocol,
                                      const base::TimeDelta& rtt) = 0;
 
+  // Called when an updated packet count at the transport layer is available.
+  // |protocol| is the protocol that was used by the watcher.
+  // |num_packets_lost| is the number of packets lost.
+  // |num_packets_received_in_order| is the number of packets received in
+  // order. |num_packets_received_not_in_order| is the number of packets
+  // received out of order. All the counts are since the last call to the
+  // OnUpdatedPacketCountAvailable. This method is called immediately after the
+  // observation is made, hence no timestamp.
+  //
+  // As an example, assume that the packets with sequence number 1, 2 and 5 have

[bengr, 2016/02/19 00:45:08]

I would be much more concise here. See my earlier comment on how to provide the
example.

[tbansal1, 2016/02/26 01:15:00]

Done.

+  // been received. Four cases are possible: (i) If next, a packet with sequence
+  // number 6 is received, then this function should be called with
+  // |num_packets_received_in_order| set to 1, and all other counts set to zero.
+  // (ii) If packet with sequence number 3 is received,
+  // |num_packets_received_not_in_order| should be set to 1, and all other
+  // counts
+  // should be zero.
+  // (iii) If packet with sequence number 2 is received again,
+  // |num_packets_received_not_in_order| should be set to 1, and all other
+  // counts
+  // should be zero.
+  // (iv) If packet with sequence number 10 is received,
+  // |num_packets_received_in_order| should be set to 1, |num_packets_lost|
+  // should be set to 4, and |num_packets_received_not_in_order| should be set
+  // to zero.
+  virtual void OnUpdatedPacketCountAvailable(
+      Protocol protocol,
+      uint64_t num_packets_lost,
+      uint64_t num_packets_received_in_order,
+      uint64_t num_packets_received_not_in_order) = 0;
+
  protected:
   SocketPerformanceWatcherFactory() {}