Make QuicPacketWriter keep track of socket writability; expose the

net/quic/quic_default_packet_writer.h

Index: net/quic/quic_default_packet_writer.h
diff --git a/net/quic/quic_default_packet_writer.h b/net/quic/quic_default_packet_writer.h
index 896998796ba3de30a6e07919dd58b59e5b365857..92543604fab1861820767ba76f64ffe060107413 100644
--- a/net/quic/quic_default_packet_writer.h
+++ b/net/quic/quic_default_packet_writer.h
@@ -32,6 +32,8 @@ class NET_EXPORT_PRIVATE QuicDefaultPacketWriter : public QuicPacketWriter {
       const net::IPEndPoint& peer_address,
       QuicBlockedWriterInterface* blocked_writer) OVERRIDE;
   virtual bool IsWriteBlockedDataBuffered() const OVERRIDE;
+  virtual bool IsWriteBlocked() const OVERRIDE;
+  virtual void SetWritable() OVERRIDE;
 
   void OnWriteComplete(int rv);
   void SetConnection(QuicConnection* connection) {
@@ -42,6 +44,7 @@ class NET_EXPORT_PRIVATE QuicDefaultPacketWriter : public QuicPacketWriter {
   base::WeakPtrFactory<QuicDefaultPacketWriter> weak_factory_;
   DatagramClientSocket* socket_;
   QuicConnection* connection_;
+  bool write_blocked_;
 };
 
 }  // namespace net