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..ef4cb9e8caabd387e907205ecaf15f7d95720cfa 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 <stddef.h>
+
 #include "base/macros.h"
 #include "base/memory/scoped_ptr.h"
 #include "net/base/net_export.h"
@@ -42,6 +44,17 @@ class NET_EXPORT_PRIVATE SocketPerformanceWatcherFactory {
   virtual void OnUpdatedRTTAvailable(const Protocol protocol,
                                      const base::TimeDelta& rtt) = 0;
 
+  // Called when the incremental packet counts at the transport layer are
+  // available. |protocol| is the protocol that was used by the watcher. All
+  // the counts are since the last call to the
+  // OnIncrementalPacketCountAvailable(). This method is called immediately
+  // after the observation is made, hence no timestamp.
+  virtual void OnIncrementalPacketCountAvailable(
+      Protocol protocol,
+      size_t packets_missing,
+      size_t packets_received_in_order,
+      size_t packets_received_out_of_order) = 0;
+
  protected:
   SocketPerformanceWatcherFactory() {}