QUIC - disable QUIC under recent pathological connection errors.

net/quic/quic_types.h

Index: net/quic/quic_types.h
diff --git a/net/quic/quic_types.h b/net/quic/quic_types.h
index 01415bc3607b9fee2516c02a71a84cb780c5ba3e..ae59b70357bd32eb4c645663f33fd21df2b24c5e 100644
--- a/net/quic/quic_types.h
+++ b/net/quic/quic_types.h
@@ -51,6 +51,18 @@ enum WriteStatus {
   WRITE_STATUS_ERROR,
 };
 
+// Reasons we may disable QUIC, that is under certain pathological
+// connection errors.  Note: these values must be kept in sync with
+// the corresponding values of QuicDisabledReason in:
+// tools/metrics/histograms/histograms.xml
+enum QuicDisabledReason {
+  QUIC_DISABLED_NOT = 0,  // default, not disabled
+  QUIC_DISABLED_PUBLIC_RESET_POST_HANDSHAKE = 1,
+  QUIC_DISABLED_TIMEOUT_WITH_OPEN_STREAMS = 2,
+  QUIC_DISABLED_BAD_PACKET_LOSS_RATE = 3,
+  QUIC_DISABLED_MAX = 4,
+};
+
 // A struct used to return the result of write calls including either the number
 // of bytes written or the error code, depending upon the status.
 struct NET_EXPORT_PRIVATE WriteResult {