[NTP] Remove unused resource string and TODOs.

components/ntp_snippets_strings.grdp

 <?xml version="1.0" encoding="utf-8"?>
 <grit-part>
 
   <if expr="is_android">
     <message name="IDS_SNIPPETS_DISABLED_SIGNED_OUT_INSTRUCTIONS" desc="Body of the card explaining the status of the content suggestions on the New Tab Page, when the user is signed out." formatter_data="android_java">
       To get personalized content suggested by Google, sign in to Chrome.
     </message>
     <message name="IDS_SNIPPETS_DISABLED_GENERIC_PROMPT" desc="Title of the card explaining what action the user can take to get content suggestions on the New Tab Page." formatter_data="android_java">
       Get suggested content
     </message>
     <message name="IDS_NTP_STATUS_CARD_TITLE_NO_SUGGESTIONS" desc="On the New Tab Page, title of the status card explaining that there is no new content available in the section." formatter_data="android_java">
       That’s all for now
     </message>
   </if>
 
   <message name="IDS_NTP_ARTICLE_SUGGESTIONS_SECTION_HEADER" desc="Header of the articles section, which is a list of news articles displayed as cards on the New Tab Page.">
     Articles for you
   </message>
 
   <message name="IDS_NTP_ARTICLE_SUGGESTIONS_SECTION_EMPTY" desc="On the New Tab Page, text of the card explaining to the user that they can expect to see suggested articles in this area in the future.">
     Your suggested articles appear here
   </message>
 
   <message name="IDS_NTP_RECENT_TAB_SUGGESTIONS_SECTION_HEADER" desc="Header of the recent tabs section, which is a list of pages that the user recently viewed, displayed as cards on the New Tab Page.">
     Recent tabs
   </message>
 
-  <!-- TODO(vitaliii): Remove this item when crbug.com/660343 is resolved. -->
-  <message name="IDS_NTP_UNUSED_PLACEHOLDER_WORKAROUND" desc="Please ignore this item.">
-    Ignore
-  </message>
-
   <message name="IDS_NTP_BOOKMARK_SUGGESTIONS_SECTION_HEADER" desc="Header of the bookmarks section, which is a list of the user's most recently used bookmarks displayed as cards on the New Tab Page.">
     Recent bookmarks
   </message>
 
   <message name="IDS_NTP_BOOKMARK_SUGGESTIONS_SECTION_EMPTY" desc="On the New Tab Page, text of the card explaining to the user that they can expect to see bookmarks in this area in the future.">
     Your recently visited bookmarks appear here
   </message>
 
   <message name="IDS_NTP_FOREIGN_SESSIONS_SUGGESTIONS_SECTION_HEADER" desc="Header of the foreign sessions, which is a list of the user's most recently visited tabs on other devices displayed as cards on the New Tab Page.">
     Continue from another device
   </message>
 
   <message name="IDS_NTP_SUGGESTIONS_SECTION_EMPTY" desc="On the New Tab Page, text of card explaining to the user that they can expect to see some sort of content suggestions in this area in the future.">
     Your suggestions appear here
   </message>
 
 </grit-part>