Discovery API supports specifying a tile in a URL.

chrome/common/extensions/api/experimental_discovery.idl

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // File-level comment to appease parser. Eventually this will not be necessary.
 
 namespace experimental.discovery {
 
   dictionary SuggestDetails {
     // The URL to suggest and that will be displayed in the new tab page under
     // the recommended pane.
     DOMString linkUrl;
 
     // The linkified text. It should be relatively short.
     DOMString linkText;
 
+    // The url of the image to use as a tile.
+    DOMString? urlImage;
+
     // A score indicating how interesting that suggestion is. The value must be
     // between 0 and 1. A suggestion with score 1 is twice as likely to be
     // displayed than one with a score of 0.5. Defaults to 1.
     // TODO: need minimum=0 and maximum=1.
     double? score;
   };
 
   interface Functions {
     // Suggests a URL for discovery.
     // |details|: Detailed information on the URL to suggest.
     static void suggest(SuggestDetails details);
 
     // Removes a URL that was previously suggested for discovery by this
     // extension.
     // |linkUrl|: The URl to remove from discovery. Must be exactly the same as
     // a linkUrl previously used on a call to suggest.
     static void removeSuggestion(DOMString linkUrl);
 
     // Clear all the URLs that were previously suggested for discovery by this
     // extension.
     static void clearAllSuggestions();
   };
 };