Move receive_window_ from BbrTcpSender and TcpCubicSender to

net/quic/quic_protocol.h

Index: net/quic/quic_protocol.h
diff --git a/net/quic/quic_protocol.h b/net/quic/quic_protocol.h
index 9ab807edaa5bd760c5b5feca97ce63fef3f5529c..6383677d6326b09f1710a17dbbae3bf7fb55635c 100644
--- a/net/quic/quic_protocol.h
+++ b/net/quic/quic_protocol.h
@@ -70,8 +70,11 @@ const uint32 kDefaultFlowControlSendWindow = 16 * 1024;  // 16 KB
 // algorithms.
 const size_t kMaxTcpCongestionWindow = 200;
 
-// Size of the socket receive buffer in bytes.
+// Default size of the socket receive buffer in bytes.
 const QuicByteCount kDefaultSocketReceiveBuffer = 256 * 1024;
+// Minimum size of the socket receive buffer in bytes.
+// Smaller values are ignored.
+const QuicByteCount kMinSocketReceiveBuffer = 16 * 1024;
 
 // Don't allow a client to suggest an RTT longer than 15 seconds.
 const uint32 kMaxInitialRoundTripTimeUs = 15 * kNumMicrosPerSecond;