Update Android Card Unmask prompt to rely on the controller a bit more.

ui/android/java/strings/android_ui_strings.grd

 <?xml version="1.0" encoding="UTF-8"?>
 <grit current_release="1" latest_public_release="0">
   <outputs>
     <output filename="values-am/android_ui_strings.xml" lang="am" type="android" />
     <output filename="values-ar/android_ui_strings.xml" lang="ar" type="android" />
     <output filename="values-bg/android_ui_strings.xml" lang="bg" type="android" />
     <output filename="values-ca/android_ui_strings.xml" lang="ca" type="android" />
     <output filename="values-cs/android_ui_strings.xml" lang="cs" type="android" />
     <output filename="values-da/android_ui_strings.xml" lang="da" type="android" />
     <output filename="values-de/android_ui_strings.xml" lang="de" type="android" />
@@ skipping 199 matching lines @@
       <message desc="Label for 'other' button in date picker dialog and time picker dialog, used to close the list of suggestions and open the the full date/time picker [CHAR-LIMIT=32]" name="IDS_DATE_PICKER_DIALOG_OTHER_BUTTON_LABEL">
         Other
       </message>
       <message desc="Title for the date picker dialog, which can be used to choose a date. [CHAR-LIMIT=32]" name="IDS_DATE_PICKER_DIALOG_TITLE">
         Set date
       </message>
       <message desc="Label for 'clear' button in date picker dialog and time picker dialog, used to replace the contents of a field with the empty string [CHAR-LIMIT=12]" name="IDS_DATE_PICKER_DIALOG_CLEAR">
         Clear
       </message>
 
-      <message desc="The text that explains the purpose of the card unmasking prompt." name="IDS_CARD_UNMASK_PROMPT_CONTENT_TEXT">
-        Enter the three digit verification code from the back of your card
-      </message>
       <message desc="Placeholder/hint text for the CVC input in the card unmasking prompt." name="IDS_CARD_UNMASK_INPUT_HINT">

[newt (away), 2015/01/06 22:19:40]

Side-comment: This description is not sufficient for translators. 

[Evan Stade, 2015/01/06 22:23:54]

How would you like to see it improved? I think "placeholder/hint text for the
CVC input" plus the English version ("CVC") should be enough. Extra context
about what the dialog is used for is not going to be relevant.

         CVC
       </message>
 
     </messages>
   </release>
 </grit>