[CrOS Tether] Add HasConnectedToHost property for Tether networks.

chromeos/network/tether_constants.cc

Index: chromeos/network/tether_constants.cc
diff --git a/chromeos/network/tether_constants.cc b/chromeos/network/tether_constants.cc
index 72fd96b32a4e44fd63937e324d817ae476db1898..1a80364e7e70333ba57430b52df74aeeeca12bd8 100644
--- a/chromeos/network/tether_constants.cc
+++ b/chromeos/network/tether_constants.cc
@@ -9,6 +9,7 @@ namespace chromeos {
 const char kTypeTether[] = "wifi-tether";
 const char kTetherBatteryPercentage[] = "Tether.BatteryPercentage";
 const char kTetherCarrier[] = "Tether.Carrier";
+const char kTetherHasConnectedToHost[] = "Tether.HasConnectedToHost";
 const char kTetherSignalStrength[] = "Tether.SignalStrength";
 const char kTetherDevicePath[] = "tether-device-path";
 const char kTetherDeviceName[] = "tether-name";