[CUPS] Implement the Webui handler for the printers auto discovery.

chrome/app/settings_strings.grdp

 <?xml version="1.0" encoding="utf-8"?>
 <!-- Settings-specific strings (included from generated_resources.grd). -->
 <grit-part>
   <!-- About Page -->
   <if expr="chromeos">
     <message name="IDS_SETTINGS_ABOUT_PAGE_DETAILED_BUILD_INFO" desc="Label describing the section that shows detailed information about the current Chrome build.">
       Detailed build information
     </message>
     <message name="IDS_SETTINGS_ABOUT_PAGE_ARC_VERSION" desc="Label for ARC version">
       ARC Version
@@ skipping 837 matching lines @@
     </message>
     <message name="IDS_SETTINGS_PRINTING_CUPS_PRINTER_MANUFACTURER" desc="Label for the dropdown menu to select a manufacturer for the printer.">
       Manufacturer
     </message>
     <message name="IDS_SETTINGS_PRINTING_CUPS_PRINTER_SELECT_DRIVER" desc="Label for the file selector to manually select a PPD file from the user's file system.">
       Or specify your own driver:
     </message>
     <message name="IDS_SETTINGS_PRINTING_CUPS_PRINTER_BUTTON_SELECT_DRIVER" desc="Text for the button which allows user to select a PPD file from the file system.">
       Browse
     </message>
-    <message name="IDS_SETTINGS_PRINTING_CUPS_PRINTER_ADDED_PRINTER_MESSAGE" desc="The message shown when a new printer is set up successfully.">
+    <message name="IDS_SETTINGS_PRINTING_CUPS_PRINTER_ADDED_PRINTER_DONE_MESSAGE" desc="The message shown when a new printer is set up successfully.">
       Added <ph name="PRINTER_NAME">$1<ex>printer</ex></ph>
     </message>
+    <message name="IDS_SETTINGS_PRINTING_CUPS_PRINTER_NO_PRINTER_NEARBY" desc="The no-printer-found message shown in the auto discovery dialog.">
+      No printers nearby
+    </message>
+    <message name="IDS_SETTINGS_PRINTING_CUPS_PRINTER_SEARCHING_NEARBY_PRINTER" desc="The searching-in-progress message shown in the auto discovery dialog.">
+      Searching...
+    </message>
+    <message name="IDS_SETTINGS_PRINTING_CUPS_PRINTER_ADDED_PRINTER_ERROR_MESSAGE" desc="The message shown when a new printer is not set up successfully.">
+      Error adding printer
+    </message>
+    <message name="IDS_SETTINGS_PRINTING_CUPS_PRINTER_ADDED_PRINTER_TRY_AGAIN_MESSAGE" desc="The try-again message shown when a new printer is not set up successfully.">
+      Try again
+    </message>  
   </if>
   <message name="IDS_SETTINGS_PRINTING_CLOUD_PRINTERS" desc="In Printing Settings, the title of the google cloud printers setting section.">
     Google Cloud Print
   </message>
   <message name="IDS_SETTINGS_PRINTING_CLOUD_PRINTERS_DESCRIPTION" desc="In Printing Settings, the title description of the google cloud printers setting section.">
     Setup cloud printing devices
   </message>
 
   <!-- Downloads Page -->
   <message name="IDS_SETTINGS_DOWNLOADS" desc="Name of the settings page which displays download preferences.">
@@ skipping 1494 matching lines @@
       System
     </message>
     <message name="IDS_SETTINGS_SYSTEM_HARDWARE_ACCELERATION_LABEL" desc="Label for the checkbox that forces Chrome to render via hardware acceleration (GPU) when available.">
       Use hardware acceleration when available
     </message>
     <message name="IDS_SETTINGS_SYSTEM_PROXY_SETTINGS_BUTTON" desc="Text for the button that changes a user's network proxy settings.">
       Change proxy settings
     </message>
   </if>
 </grit-part>