QUIC - add new UMA histograms to help understand HPACK head of line blocking.

net/quic/quic_chromium_client_session.h

Index: net/quic/quic_chromium_client_session.h
diff --git a/net/quic/quic_chromium_client_session.h b/net/quic/quic_chromium_client_session.h
index fff5d972b8808425bc0dc6577b9264f1cd60b51f..499731f82570284ed36501b10e9a174206d304cf 100644
--- a/net/quic/quic_chromium_client_session.h
+++ b/net/quic/quic_chromium_client_session.h
@@ -136,6 +136,8 @@ class NET_EXPORT_PRIVATE QuicChromiumClientSession
       NetLog* net_log);
   ~QuicChromiumClientSession() override;
 
+  void Initialize() override;
+
   void AddObserver(Observer* observer);
   void RemoveObserver(Observer* observer);
 
@@ -277,6 +279,14 @@ class NET_EXPORT_PRIVATE QuicChromiumClientSession
       QuicStreamId id) override;
 
  private:
+  class HpackEncoderDebugVisitor : public QuicHeadersStream::HpackDebugVisitor {
+    void OnUseEntry(const QuicTime::Delta elapsed) override;
+  };
+
+  class HpackDecoderDebugVisitor : public QuicHeadersStream::HpackDebugVisitor {
+    void OnUseEntry(const QuicTime::Delta elapsed) override;
+  };

[Ryan Hamilton, 2016/05/20 21:27:18]

Looks like these can be moved to the .cc file.

[Buck, 2016/05/20 21:41:31]

Done.

+
   friend class test::QuicChromiumClientSessionPeer;
 
   typedef std::set<Observer*> ObserverSet;