arc: Add explicit error message in case network cannot be setup.

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 6574 matching lines @@
   </message>
   <message name="IDS_ARC_SIGN_IN_UNKNOWN_ERROR" desc="Android sign-in error because of unknown error">
     Unknown error
   </message>
   <message name="IDS_ARC_SERVER_COMMUNICATION_ERROR" desc="Android sign-in error because of server communication error">
     Server communication error
   </message>
   <message name="IDS_ARC_ANDROID_MANAGEMENT_REQUIRED_ERROR" desc="Error message shown when Android management is required for an unmanaged Chrome OS user.">
     Your organization has not enabled Google Play Store for your account. Contact your administrator for more information.
   </message>
+  <message name="IDS_ARC_NETWORK_UNAVAILABLE_ERROR" desc="Error message shown when Android cannot set up network connection.">
+    Network connection cannot be established.
+  </message>
   <message name="IDS_ARC_CRITICALLY_LOW_DISK_NOTIFICATION_TITLE" desc="Title of the notification warning users that they are critically low on disk space and Android apps can not be launched.">
     Device disk space critically low
   </message>
   <message name="IDS_ARC_CRITICALLY_LOW_DISK_NOTIFICATION_MESSAGE" desc="Notification text warning users that they are critically low on disk space and Android apps can not be launched.">
     Free up disk space to launch Android apps.
   </message>
   <message name="IDS_ARC_OOBE_TERMS_HEADING" desc="Heading of the Arc Terms OOBE dialog.">
     Google Play Terms of Service
   </message>
   <message name="IDS_ARC_OOBE_TERMS_DESCRIPTION" desc="Description of the Arc Terms OOBE dialog.">
@@ skipping 103 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>