[CrOS Tether] Add tether settings section to the MD settings page.

ui/webui/resources/cr_elements/network/cr_onc_types.js

Index: ui/webui/resources/cr_elements/network/cr_onc_types.js
diff --git a/ui/webui/resources/cr_elements/network/cr_onc_types.js b/ui/webui/resources/cr_elements/network/cr_onc_types.js
index 06303bd60a20561a8f579f324f0179c3e32c7598..3b42f1e0bc4ba62a2d6aabaaa568e8ccaf72e9e1 100644
--- a/ui/webui/resources/cr_elements/network/cr_onc_types.js
+++ b/ui/webui/resources/cr_elements/network/cr_onc_types.js
@@ -211,7 +211,7 @@ CrOnc.getActiveValue = function(property) {
 };
 
 /**
- * Return the acitve value for a managed or unmanaged string property.
+ * Return the active value for a managed or unmanaged string property.
  * @param {!CrOnc.ManagedProperty|string|undefined} property
  * @return {string}
  */
@@ -308,6 +308,8 @@ CrOnc.getSignalStrength = function(properties) {
   var type = properties.Type;
   if (type == CrOnc.Type.CELLULAR && properties.Cellular)
     return properties.Cellular.SignalStrength || 0;
+  if (type == CrOnc.Type.TETHER && properties.Tether)
+    return properties.Tether.SignalStrength || 0;
   if (type == CrOnc.Type.WI_FI && properties.WiFi)
     return properties.WiFi.SignalStrength || 0;
   if (type == CrOnc.Type.WI_MAX && properties.WiMAX)