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

chrome/app/chromeos_strings.grdp

 <?xml version="1.0" encoding="utf-8"?>
 <!-- Chrome OS-specific strings (included from generated_resources.grd).
      Everything in this file is wrapped in <if expr="chromeos">. -->
 <grit-part>
   <message name="IDS_EMPTY_STRING" desc="Empty string, exist only to make code generic. No translation required.">
   </message>
   <!-- Idle logout dialog for retail mode -->
   <message name="IDS_IDLE_LOGOUT_TITLE" desc="Dialog title for the idle logout dialog. Used in retail mode only.">
     Are you still there?
   </message>
@@ skipping 3862 matching lines @@
   </message>
   <message name="IDS_STATUSBAR_NETWORK_DEVICE_WIFI" desc="Label for a wifi network device.">
     Wi-Fi
   </message>
   <message name="IDS_STATUSBAR_NETWORK_DEVICE_CELLULAR" desc="Label for a cellular network device.">
     Mobile Data
   </message>
   <message name="IDS_NETWORK_TYPE_ETHERNET" desc="The ethernet network type.">
     Ethernet
   </message>
+  <message name="IDS_NETWORK_TYPE_TETHER" desc="The tether network type.">
+    Tether
+  </message>
   <message name="IDS_NETWORK_TYPE_WIFI" desc="The wifi network type.">
     Wi-Fi
   </message>
   <message name="IDS_NETWORK_TYPE_WIMAX" desc="The wimax network type.">
     WiMAX
   </message>
   <message name="IDS_NETWORK_TYPE_BLUETOOTH" desc="The bluetooth network type.">
     Bluetooth
   </message>
   <message name="IDS_NETWORK_TYPE_CELLULAR" desc="The cellular network type.">
@@ skipping 2805 matching lines @@
     Attempts left: $1
   </message>
   <message name="IDS_REQUEST_PIN_DIALOG_PIN" desc="The Provider Identification Number abbreviation">
     PIN
   </message>
   <message name="IDS_REQUEST_PIN_DIALOG_PUK" desc="The Personal Unlocking Key (as used in mobile phones) abbreviation">
     PUK
   </message>
 
 </grit-part>