Return a new error code for multi-install updates if Group Policy settings blocking...

chrome/app/google_chrome_strings.grd

 <?xml version="1.0" encoding="UTF-8"?>
 <!-- This file contains definitions of strings that are specific to
 Google Chrome. These strings will be translated for each locale that Google
 Chrome supports. -->
 
 <grit base_dir="." latest_public_release="0" current_release="1"
       source_lang_id="en" enc_check="möl">
   <outputs>
     <output filename="grit/google_chrome_strings.h" type="rc_header">
       <emit emit_type='prepend'></emit>
@@ skipping 440 matching lines @@
       </message>
       <message name="IDS_INSTALL_MULTI_INSTALLATION_EXISTS" desc="Error during install if a multi-install Google Chrome or Google Chrome Frame is present, thereby preventing the installation of a single-install Google Chrome or Google Chrome Frame.">
         A conflicting installation of Google Chrome or Google Chrome Frame was found on the system. Please uninstall it and try again.
       </message>
       <message name="IDS_INSTALL_CONFLICTING_CHANNEL_EXISTS" desc="Error during install if a version of Google Chrome on a different update channel exists when installing Google Chrome Frame.">
         A conflicting installation of Google Chrome was found on the system. Please uninstall it and try again.
       </message>
       <message name="IDS_INSTALL_READY_MODE_REQUIRES_CHROME" desc="Chrome Frame in ready mode requires Chrome.">
         Invalid arguments. Google Chrome Frame cannot be installed in ready mode without also installing Google Chrome.
       </message>
+      <message name="IDS_INSTALL_INCONSISTENT_UPDATE_POLICY" desc="Error during install if the update policies settings in Group Policy are inconsistent.">
+        Google Chrome or Google Chrome Frame cannot be updated on account of inconsistent Google Update Group Policy settings. Use the Group Policy Editor to set the update policy override for the Google Chrome Binaries application and try again.
+      </message>
       <!-- Options Dialog -->
       <message name="IDS_OPTIONS_IMPROVE_BROWSING_EXPERIENCE" desc="The text in the options panel that describes how we use web services to improve browsing experience.">
         Google Chrome may use web services to improve your browsing experience.
       </message>
       <message name="IDS_IMPORT_BOOKMARKS" desc="Explanatory text for the importing progress dialog when importing a bookmarks.html file from the bookmark manager">
         Google Chrome is now importing Favorites/Bookmarks.
       </message>
       <message name="IDS_OEM_MAIN_SHORTCUT_NAME" desc="Name of the desktop shortcut to start the application for OEM pre-installations.">
         Internet Browser
       </message>
@@ skipping 96 matching lines @@
         <message name="IDS_UTILITY_APP_NAME" desc="The utility application's name.  Should contain the Chrome application name (IDS_PRODUCT_NAME). Example: Google Chrome Utility.">
           Google Chrome Utility
         </message>
         <message name="IDS_SHORT_UTILITY_APP_NAME" desc="The utility application's short name, used for the Mac's application menu, activity monitor, etc. Example: Chrome Utility, not Google Chrome Utility.">
           Chrome Utility
         </message>
       </if>
     </messages>
   </release>
 </grit>