[MD Settings] Add a menu option to clear a cached credit card.

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_CHECK_FOR_UPDATES" desc="The button label to check for updates and apply (download and install) if found">
       Check for updates
     </message>
     <message name="IDS_SETTINGS_ABOUT_PAGE_CURRENT_CHANNEL_STABLE" desc="The stable label in the message about current channel.">
       stable
@@ skipping 236 matching lines @@
   </message>
   <message name="IDS_SETTINGS_ADDRESS_REMOVE" desc="Label for a context menu item that removes the selected address." meaning="Remove selected address.">
    Remove
   </message>
   <message name="IDS_SETTINGS_CREDIT_CARD_EDIT" desc="Label for a context menu item that shows a dialog with edit options for the selected credit card." meaning="Edit selected credit card.">
    Edit
   </message>
   <message name="IDS_SETTINGS_CREDIT_CARD_REMOVE" desc="Label for a context menu item that removes the selected credit card." meaning="Remove selected credit card.">
    Remove
   </message>
+  <message name="IDS_SETTINGS_CREDIT_CARD_CLEAR" desc="Label for a context menu item clears the locally cached credit card that is also saved on Google Payments. Clicking this will NOT remove the credit card from Google Payments.">
+   Clear copy
+  </message>
   <message name="IDS_SETTINGS_EDIT_CREDIT_CARD_TITLE" desc="The title for the dialog that's shown when editing a credit card.">
     Edit credit card
   </message>
   <message name="IDS_SETTINGS_ADD_CREDIT_CARD_TITLE" desc="The title for the dialog that's shown when entering the information for a new credit card.">
     Add credit card
   </message>
   <message name="IDS_SETTINGS_NAME_ON_CREDIT_CARD" desc="The title for the input that lets users modify the name on the credit card.">
     Name on card
   </message>
   <message name="IDS_SETTINGS_CREDIT_CARD_NUMBER" desc="The title for the input that lets users modify the credit card number for a credit card.">
@@ skipping 1348 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>