Remove unused histograms: Net.QuicSession.21* & Net.QuicSession.6*

net/quic/quic_connection_logger.h

Index: net/quic/quic_connection_logger.h
diff --git a/net/quic/quic_connection_logger.h b/net/quic/quic_connection_logger.h
index ff2c9173e1a988f0c481887b0f354b0f1d5bcc66..6406d2f443e12fdcf328d693ee176a50ecac8067 100644
--- a/net/quic/quic_connection_logger.h
+++ b/net/quic/quic_connection_logger.h
@@ -94,27 +94,6 @@ class NET_EXPORT_PRIVATE QuicConnectionLogger
   // element of data is recorded, and is used to form the histogram name.
   base::HistogramBase* GetPacketNumberHistogram(
       const char* statistic_name) const;
-  // Do a factory get for a histogram to record a 6-packet loss-sequence as a
-  // sample. The histogram will record the 64 distinct possible combinations.
-  // |which_6| is used to adjust the name of the histogram to distinguish the
-  // first 6 packets in a connection, vs. some later 6 packets.
-  base::HistogramBase* Get6PacketHistogram(const char* which_6) const;
-  // Do a factory get for a histogram to record cumulative stats across a 21
-  // packet sequence.  |which_21| is used to adjust the name of the histogram
-  // to distinguish the first 21 packets' loss data, vs. some later 21 packet
-  // sequences' loss data.
-  base::HistogramBase* Get21CumulativeHistogram(const char* which_21) const;
-  // Add samples associated with a |bit_mask_of_packets| to the given histogram
-  // that was provided by Get21CumulativeHistogram().  The LSB of that mask
-  // corresponds to the oldest packet number in the series of packets,
-  // and the bit in the 2^20 position corresponds to the most recently received
-  // packet.  Of the maximum of 21 bits that are valid (correspond to packets),
-  // only the most significant |valid_bits_in_mask| are processed.
-  // A bit value of 0 indicates that a packet was never received, and a 1
-  // indicates the packet was received.
-  static void AddTo21CumulativeHistogram(base::HistogramBase* histogram,
-                                         int bit_mask_of_packets,
-                                         int valid_bits_in_mask);
   // For connections longer than 21 received packets, this call will calculate
   // the overall packet loss rate, and record it into a histogram.
   void RecordAggregatePacketLossRate() const;