relnote: Add a method in QuicSession to expose the number of draining streams.

Manual merge internal change: 197808559

Change-Id: I89c702716274264e629708324bca6cce89a95abd
Reviewed-on: https://chromium-review.googlesource.com/1073924Reviewed-by: Ryan Hamilton <rch@chromium.org>
Commit-Queue: Zhongyi Shi <zhongyi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#562513}

net/third_party/quic/core/quic_session.cc

@@ -944,6 +944,10 @@ size_t QuicSession::GetNumActiveStreams() const {
   return dynamic_stream_map_.size() - draining_streams_.size();
 }
 
+size_t QuicSession::GetNumDrainingStreams() const {
+  return draining_streams_.size();
+}
+
 size_t QuicSession::GetNumAvailableStreams() const {
   return available_streams_.size();
 }

net/third_party/quic/core/quic_session.h

@@ -238,6 +238,9 @@ class QUIC_EXPORT_PRIVATE QuicSession : public QuicConnectionVisitorInterface,
   // headers and crypto streams, and never counting unfinished streams.
   size_t GetNumActiveStreams() const;
 
+  // Returns the number of currently draining streams.
+  size_t GetNumDrainingStreams() const;
+
   // Returns the number of currently open peer initiated streams, excluding the
   // reserved headers and crypto streams.
   size_t GetNumOpenIncomingStreams() const;