Remove --enable-firewall-hole-punching flag, default to enabled.

chrome/app/chromeos_strings.grdp

 <?xml version="1.0" encoding="utf-8"?>
 <!-- ChromeOS-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>
   <message name="IDS_CHROMEBOOK" desc="The localized name for Chromebook.">
     Chromebook
   </message>
   <message name="IDS_CHROMEBOX" desc="The localized name for Chromebox">
@@ skipping 6303 matching lines @@
   </message>
   <message name="IDS_FLAGS_DISABLE_WEBVIEW_SIGNIN_FLOW_NAME" desc="Title for the flag to disable the new WebView-based sign-in flow.">
     Disable WebView-based sign-in flow
   </message>
   <message name="IDS_FLAGS_DISABLE_WEBVIEW_SIGNIN_FLOW_DESCRIPTION" desc="Description for the flag to disable the new WebView-based sign-in flow.">
     If set, sign-in will be performed using the old GAIA flow instead of the new WebView-based one.
   </message>
   <message name="IDS_OPTIONS_RESOLVE_TIMEZONE_BY_GEOLOCATION_DESCRIPTION" desc="Label for checkbox to allow automatic timezone update by user geolocation.">
     Set time zone automatically using your location
   </message>
-  <message name="IDS_FLAGS_ENABLE_FIREWALL_HOLE_PUNCHING_NAME" desc="Name of the option to enable punching holes in the Chrome OS firewall.">
-    Enable firewall hole punching.
-  </message>
-  <message name="IDS_FLAGS_ENABLE_FIREWALL_HOLE_PUNCHING_DESCRIPTION" desc="Description of the option to enable punching holes in the Chrome OS firewall.">
-    Enable punching holes in the Chrome OS firewall for Chrome Apps that open a TCP/IP server socket or UDP socket.
-  </message>
   <message name="IDS_FILE_SYSTEM_REQUEST_FILE_SYSTEM_DIALOG_TITLE" desc="Title of a prompt dialog for granting permissions to a volume (eg. USB drive, SD card, MTP device) with the specified name.">
     Permission requested
   </message>
   <message name="IDS_FILE_SYSTEM_REQUEST_FILE_SYSTEM_DIALOG_MESSAGE" desc="Message in a prompt dialog for granting read-only permissions to a volume (eg. USB drive, SD card, MTP device) with the specified name to the extension.">
     <ph name="APP_NAME">$1<ex>Super Kiosk app</ex></ph> wants to copy files from <ph name="VOLUME_NAME">$2<ex>FooBar 4GB</ex></ph>.
   </message>
   <message name="IDS_FILE_SYSTEM_REQUEST_FILE_SYSTEM_DIALOG_WRITABLE_MESSAGE" desc="Message in a prompt dialog for granting full permissions (read, write, delete, create files and directories) to a volume (eg. USB drive, SD card, MTP device) with the specified name to the extension.">
     <ph name="APP_NAME">$1<ex>Super Kiosk app</ex></ph> wants to access <ph name="VOLUME_NAME">$2<ex>FooBar 4GB</ex></ph>. It may modify or delete your files.
   </message>
   <message name="IDS_FILE_SYSTEM_REQUEST_FILE_SYSTEM_DIALOG_ALLOW_BUTTON" desc="Label on the button to grant permissions.">
@@ skipping 23 matching lines @@
     An app that shows a filtered list of extensions from Chrome Web Store. Extensions in the list can be installed directly from the app.
   </message>
   <message name="IDS_WEBSTORE_WIDGET_TITLE_PRINTER_PROVIDERS" desc="Title for Chrome Web Store Gallery Widget which lists all print driver apps from Chrome Web Store for a specific printer.">
     Select a printer driver app
   </message>
   <message name="IDS_WEBSTORE_WIDGET_DEFAULT_ERROR" desc="Default message shown when Chrome Web Store Widget app window content fails to load (e.g. if it fails to load Chrome Web Store Gallery in a webview).">
     Could not connect to the Chrome Web Store.
   </message>
 
 </grit-part>