Add support for components/ntp_tiles in InstantService

components/ntp_tiles/ntp_tile.h

Index: components/ntp_tiles/ntp_tile.h
diff --git a/components/ntp_tiles/ntp_tile.h b/components/ntp_tiles/ntp_tile.h
index ef228b54b385dfe68d82c4265150dbcd23757d9b..9af8614398bf3d0632ea6ab07264e495ae575607 100644
--- a/components/ntp_tiles/ntp_tile.h
+++ b/components/ntp_tiles/ntp_tile.h
@@ -37,6 +37,10 @@ struct NTPTile {
   // Only valid for source == WHITELIST (empty otherwise).
   base::FilePath whitelist_icon_path;
 
+  // Only valid for source == SUGGESTIONS_SERVICE (empty otherwise).

[sfiera, 2016/11/28 13:11:12]

Are they always non-empty for the suggestions service? What happens if a site
doesn't have a favicon, or we haven't yet visited it to produce the thumbnail?

[Marc Treib, 2016/11/28 13:19:29]

I believe the favicon URL always points to some chrome://favicons/ URL, and may
or may not 404.

The thumbnail URL can point to a local chrome:// (or chrome-search://, I forget)
URL and/or an online URL pointing to a thumbnail service. I think it can be
empty in some cases.

[sfiera, 2016/11/29 10:24:03]

I would appreciate this kind of information in the comment :)

[Marc Treib, 2016/11/29 15:20:13]

Not sure how much of this we want to "fixate" in the API - e.g. the favicon URL
may be passed down from the server (though that doesn't happen in practice these
days AFAIK).
Well, I tried to add some info, PTAL.

+  GURL thumbnail_url;
+  GURL favicon_url;
+
   NTPTile();
   NTPTile(const NTPTile&);
   ~NTPTile();