chromeos: Add OS credits link to about page.

chrome/app/chromium_strings.grd

 <?xml version="1.0" encoding="UTF-8"?>
 <!-- This file contains definitions of strings that are distribution specific.
 These strings will not be translated and only english versions will
 be available for now. -->
 
 <grit base_dir="." latest_public_release="0" current_release="1"
       source_lang_id="en" enc_check="möl">
   <outputs>
     <output filename="grit/chromium_strings.h" type="rc_header">
       <emit emit_type='prepend'></emit>
@@ skipping 181 matching lines @@
       </message>
       <message name="IDS_ABOUT_VERSION_COMPANY_NAME" desc="Company name on the about pages">
         The Chromium Authors
       </message>
       <message name="IDS_ABOUT_VERSION_COPYRIGHT" desc="Copyright information on the about pages">
         Copyright © 2006-2010 The Chromium Authors. All Rights Reserved.
       </message>
       <message name="IDS_ABOUT_VERSION_LICENSE" desc="The label below the copyright message, containing the URLs.">
         Chromium is made possible by the <ph name="BEGIN_LINK_CHROMIUM">BEGIN_LINK_CHR</ph>Chromium<ph name="END_LINK_CHROMIUM">END_LINK_CHR</ph> open source project and other <ph name="BEGIN_LINK_OSS">BEGIN_LINK_OSS</ph>open source software<ph name="END_LINK_OSS">END_LINK_OSS</ph>.
       </message>
+      <if expr="pp_ifdef('chromeos')">
+        <message name="IDS_ABOUT_CROS_VERSION_LICENSE" desc="Additional text displayed beneath the Chromium open source URLs for Chromium OS.">
+          Chromium OS is made possible by additional <ph name="BEGIN_LINK_CROS_OSS">BEGIN_LINK_CROS_OSS</ph>open source software<ph name="END_LINK_CROS_OSS">END_LINK_CROS_OSS</ph>.
+        </message>
+      </if>
       <message name="IDS_ABOUT_TERMS_OF_SERVICE" desc="The terms of service label in the About box.">
         Not used in Chromium. Placeholder to keep resource maps in synch.
       </message>
       <message name="IDS_TERMS_OF_SERVICE" desc="The Terms of Service link text in the About box. Used in IDS_ABOUT_TERMS_OF_SERVICE.">
         Not used in Chromium. Placeholder to keep resource maps in synch.
       </message>
       <message name="IDS_ACCNAME_APP" desc="The accessible name for the app menu.">
         Chromium
       </message>
       <message name="IDS_ACCNAME_TOOLBAR" desc="The accessible name for the application's toolbar.">
@@ skipping 287 matching lines @@
         <message name="IDS_PROFILEIMPORTER_APP_NAME" desc="The profile importer application's name.  Should contain the Chrome application name (IDS_PRODUCT_NAME). Example: Google Chrome Profile Importer.">
           Chromium Profile Importer
         </message>
         <message name="IDS_SHORT_PROFILEIMPORTER_APP_NAME" desc="The profile importer application's short name, used for the Mac's application menu, activity monitor, etc. Example: Chrome Profile Importer, not Google Chrome Profile Importer.">
           Chromium Profile Importer
         </message>
       </if>
     </messages>
   </release>
 </grit>