Added prefs ui for enabling/disabling background mode on windows.

chrome/app/resources/locale_settings.grd

 <?xml version="1.0" encoding="UTF-8"?>
 <grit latest_public_release="0" current_release="1">
   <outputs>
     <output filename="grit/locale_settings.h" type="rc_header">
       <emit emit_type='prepend'></emit>
     </output>
     <output filename="locale_settings_am.rc" type="rc_all" lang="am" />
     <output filename="locale_settings_ar.rc" type="rc_all" lang="ar" />
     <output filename="locale_settings_bg.rc" type="rc_all" lang="bg" />
     <output filename="locale_settings_bn.rc" type="rc_all" lang="bn" />
@@ skipping 491 matching lines @@
       <!-- The URL for the the Welcome to Chrome page shown on first run. -->
       <message name="IDS_WELCOME_PAGE_URL" translateable="false">
         http://tools.google.com/chrome/intl/[GRITLANGCODE]/welcome.html
       </message>
 
       <!-- The URL for the "Learn more" page for the Privacy section under Options. -->
       <message name="IDS_LEARN_MORE_PRIVACY_URL" translateable="false">
         http://www.google.com/support/chrome/bin/answer.py?answer=114836&amp;hl=[GRITLANGCODE]
       </message>
 
+      <!-- The URL for the "Learn more" page for the Chrome Web Apps section under Options.-->
+      <message name="IDS_LEARN_MORE_BACKGROUND_MODE_URL" translateable="false">
+        http://www.google.com/support/chrome/bin/answer.py?answer=188022&amp;hl=[GRITLANGCODE]
+      </message>
+
       <!-- The URL for the "Learn more" page for the usage/crash reporting option in the first run dialog. -->
       <message name="IDS_LEARN_MORE_REPORTING_URL" translateable="false">
         http://www.google.com/support/chrome/bin/answer.py?answer=96817&amp;hl=[GRITLANGCODE]
       </message>
 
       <!-- The URL for the "Learn more" privacy page for the Geolocation permission infobar. -->
       <message name="IDS_LEARN_MORE_GEOLOCATION_URL" translateable="false">
         http://www.google.com/support/chrome/bin/answer.py?answer=142065&amp;hl=[GRITLANGCODE]
       </message>
 
@@ skipping 174 matching lines @@
         <message name="IDS_PASSWORD_CHANGED_DIALOG_WIDTH_CHARS" use_name_for_id="true">
           70
         </message>
         <message name="IDS_PASSWORD_CHANGED_DIALOG_HEIGHT_LINES" use_name_for_id="true">
           14
         </message>
       </if>
     </messages>
   </release>
 </grit>