[CrOS Tether] Disconnect cleanly from active Tether networks when the user logs out or the Tether c…

chromeos/components/tether/pref_names.h

Index: chromeos/components/tether/pref_names.h
diff --git a/chromeos/components/tether/pref_names.h b/chromeos/components/tether/pref_names.h
index fa81731ef54970ee8ba78c5784034563e4958a6b..9b772777f9931a2d41ea0102a1ccee2c6a791280 100644
--- a/chromeos/components/tether/pref_names.h
+++ b/chromeos/components/tether/pref_names.h
@@ -39,6 +39,17 @@ extern const char kTetherNetworkGuid[];
 // value at this key is "".
 extern const char kWifiNetworkGuid[];
 
+// The Wi-Fi network GUID that is currently being disconnected. When
+// disconnecting under normal circumstances, this value is set when a
+// disconnection is initiated and is cleared when a disconnection completes.
+// However, when a disconnection is triggered by the user logging out, the
+// disconnection flow cannot complete before Chrome shuts down (due to the
+// asynchronous nature of the network stack), so this GUID remains in prefs.
+// When the Tether component starts up again (the next time the user logs in),
+// this GUID is fetched, the associated network configuration is removed, and
+// the GUID is cleared from prefs.
+extern const char kDisconnectingWifiNetworkGuid[];
+
 }  // namespace prefs
 
 }  // namespace tether