MD Settings: Add "Auto Open" setting to Downloads page UI.

chrome/app/settings_strings.grdp

 <?xml version="1.0" encoding="utf-8"?>
 <!-- Settings-specific strings (included from generated_resources.grd). -->
 <grit-part>
   <!-- Main Page -->
   <if expr="chromeos">
     <message name="IDS_SETTINGS_SECONDARY_USER_BANNER" desc="Banner displayed in settings page when the user is secondary in a multi-profile session.">
       Some settings belonging to <ph name="PRIMARY_EMAIL">$1<ex>john@google.com</ex></ph> are being shared with you. These settings only affect your account when using multiple sign-in.
     </message>
   </if>
 
@@ skipping 977 matching lines @@
   </message>
   <message name="IDS_SETTINGS_CHANGE_DOWNLOAD_LOCATION" desc="Text for the button which allows the user to change the default download directory.">
     Change
   </message>
   <message name="IDS_SETTINGS_PROMPT_FOR_DOWNLOAD" desc="Label for the checkbox which enables a prompt for the user to choose a download location for each download instead of using the default.">
     Ask where to save each file before downloading
   </message>
   <message name="IDS_SETTINGS_DISCONNECT_GOOGLE_DRIVE" desc="Label for the checkbox which enables disconnecting from Google Drive account.">
     Disconnect Google Drive account
   </message>
+  <message name="IDS_SETTINGS_OPEN_FILE_TYPES_AUTOMATICALLY" desc="The information label for the 'Clear auto-opening settings' button">
+    Open certain file types automatically after downloading
+  </message>
 
   <if expr="chromeos">
     <!-- Date/Time Page -->
     <message name="IDS_SETTINGS_DATE_TIME" desc="Name of the settings page which displays date and time preferences.">
       Date and time
     </message>
     <message name="IDS_SETTINGS_TIME_ZONE" desc="Label for the picker which allows users to choose their time zone.">
       Time zone:
     </message>
     <message name="IDS_SETTINGS_TIME_ZONE_GEOLOCATION" desc="Label for the checkbox which enables setting the time zone automatically with the detected location of the device.">
@@ skipping 1888 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>