Add new extension API for VPN

extensions/extensions_strings.grd

 <?xml version="1.0" encoding="utf-8"?>
 
 <!--
   Strings for the extensions module. Used mostly for low-level error messages.
   Where possible new strings should be kept in Chrome and the extensions module
   should return an error code, message flag, etc.
 -->
 
 <grit latest_public_release="0" current_release="1"
       source_lang_id="en" enc_check="möl">
@@ skipping 317 matching lines @@
       </message>
       <message name="IDS_EXTENSION_PROMPT_WARNING_HID" desc="Permission string for access to HID devices.">
         Access your input devices
       </message>
       <message name="IDS_EXTENSION_PROMPT_WARNING_SERIAL" desc="Permission string for access to serial devices.">
         Access your serial devices
       </message>
       <message name="IDS_EXTENSION_PROMPT_WARNING_USB" desc="Permission string for access to USB devices.">
         Access your USB devices
       </message>
+      <message name="IDS_EXTENSION_PROMPT_WARNING_VPN" desc="Permission string for access to VPN API.">
+        Access your network traffic
+      </message>
       <message name="IDS_EXTENSION_PROMPT_WARNING_USB_DEVICE" desc="Permission string for access to a specific USB device.">
         Access the USB device <ph name="PRODUCT_NAME">$1<ex>SoundKnob</ex></ph> from <ph name="VENDOR_NAME">$2<ex>Griffin Technology</ex></ph>
       </message>
       <message name="IDS_EXTENSION_PROMPT_WARNING_USB_DEVICE_MISSING_PRODUCT" desc="Permission string for access to a specific USB device when a product name cannot be established for a USB device.">
         Access the USB device from <ph name="VENDOR_NAME">$1<ex>Griffin Technology</ex></ph>
       </message>
       <message name="IDS_EXTENSION_PROMPT_WARNING_USB_DEVICE_MISSING_VENDOR" desc="Permission string for access to a specific USB device when a vendor name cannot be established for a USB device.">
         Access the USB device
       </message>
       <message name="IDS_EXTENSION_TASK_MANAGER_APPVIEW_TAG_PREFIX" desc="The prefix for a guest page loaded in an appview tag in the Task Manager">
@@ skipping 40 matching lines @@
       <message name="IDS_EXTENSION_PROMPT_WARNING_U2F_DEVICES" desc="Warning message which indicates that an extension has access to Universal 2nd Factor devices.">
         Access your Universal 2nd Factor devices
       </message>
       <message name="IDS_EXTENSION_PROMPT_WARNING_WEB_CONNECTABLE" desc="Permission string for allowing websites to connect to extensions.">
         Communicate with cooperating websites
       </message>
 
     </messages>
   </release>
 </grit>