Add support for third-party doodles on the Android NTP

This adds a 'doodle_url' field to prepopulated_engines.json, and plumbs
it through to the LogoService. It also adds a command line flag
--third-party-doodle-url for testing, and a feature
ThirdPartyDoodles (disabled by default).

This is a follow-up to https://chromium-review.googlesource.com/c/539417
and https://crbug.com/725435.

Bug: 752453
Change-Id: Iaf6e14d5b60069ea58875ed891240bbab26d559a
Reviewed-on: https://chromium-review.googlesource.com/608136
Commit-Queue: Marc Treib <[email protected]>
Reviewed-by: Maria Khomenko <[email protected]>
Reviewed-by: Vasilii Sukhanov <[email protected]>
Reviewed-by: Bernhard Bauer <[email protected]>
Cr-Commit-Position: refs/heads/master@{#496258}
diff --git a/components/search_engines/template_url_data.h b/components/search_engines/template_url_data.h
index 6ad8be2..f970bd5 100644
--- a/components/search_engines/template_url_data.h
+++ b/components/search_engines/template_url_data.h
@@ -38,6 +38,7 @@
                   base::StringPiece new_tab_url,
                   base::StringPiece contextual_search_url,
                   base::StringPiece logo_url,
+                  base::StringPiece doodle_url,
                   base::StringPiece search_url_post_params,
                   base::StringPiece suggest_url_post_params,
                   base::StringPiece instant_url_post_params,
@@ -75,6 +76,9 @@
   // Optional URL for the logo.
   GURL logo_url;
 
+  // Optional URL for the Doodle.
+  GURL doodle_url;
+
   // The following post_params are comma-separated lists used to specify the
   // post parameters for the corresponding URL.
   std::string search_url_post_params;