Deprecate FLAGS_quic_record_send_time_before_write.

net/quic/quic_connection.cc

Index: net/quic/quic_connection.cc
diff --git a/net/quic/quic_connection.cc b/net/quic/quic_connection.cc
index f7dd621506652b61b19e78f30a307081653fd346..aca4d203b993f08ccae94da39319110ebf025d0d 100644
--- a/net/quic/quic_connection.cc
+++ b/net/quic/quic_connection.cc
@@ -1444,13 +1444,10 @@ bool QuicConnection::WritePacketInner(QueuedPacket* packet) {
   DVLOG(2) << ENDPOINT << "packet(" << sequence_number << "): " << std::endl
            << QuicUtils::StringToHexASCIIDump(encrypted->AsStringPiece());
 
-  QuicTime packet_send_time = QuicTime::Zero();
-  if (FLAGS_quic_record_send_time_before_write) {
-    // Measure the RTT from before the write begins to avoid underestimating the
-    // min_rtt_, especially in cases where the thread blocks or gets swapped out
-    // during the WritePacket below.
-    packet_send_time = clock_->Now();
-  }
+  // Measure the RTT from before the write begins to avoid underestimating the
+  // min_rtt_, especially in cases where the thread blocks or gets swapped out
+  // during the WritePacket below.
+  QuicTime packet_send_time = clock_->Now();
   WriteResult result = writer_->WritePacket(encrypted->data(),
                                             encrypted->length(),
                                             self_address().address(),
@@ -1469,16 +1466,6 @@ bool QuicConnection::WritePacketInner(QueuedPacket* packet) {
       return false;
     }
   }
-  if (!FLAGS_quic_record_send_time_before_write) {
-    packet_send_time = clock_->Now();
-  }
-  if (!packet_send_time.IsInitialized()) {
-    // TODO(jokulik): This is only needed because of the two code paths for
-    // initializing packet_send_time.  Once "quic_record_send_time_before_write"
-    // is deprecated, this check can be removed.
-    LOG(DFATAL) << "The packet send time should never be zero. "
-                << "This is a programming bug, please report it.";
-  }
   if (result.status != WRITE_STATUS_ERROR && debug_visitor_ != nullptr) {
     // Pass the write result to the visitor.
     debug_visitor_->OnPacketSent(packet->serialized_packet,
@@ -1493,10 +1480,7 @@ bool QuicConnection::WritePacketInner(QueuedPacket* packet) {
   }
   SetPingAlarm();
   MaybeSetFecAlarm(sequence_number);
-  DVLOG(1) << ENDPOINT << "time "
-           << (FLAGS_quic_record_send_time_before_write ?
-               "we began writing " : "we finished writing ")
-           << "last sent packet: "
+  DVLOG(1) << ENDPOINT << "time we began writing last sent packet: "
            << packet_send_time.ToDebuggingValue();
 
   // TODO(ianswett): Change the sequence number length and other packet creator