[Doodle] Replace the expiry_date in DoodleConfig by time_to_live

components/doodle/doodle_types.h

 // Copyright 2017 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.
 
 #ifndef COMPONENTS_DOODLE_DOODLE_TYPES_H_
 #define COMPONENTS_DOODLE_DOODLE_TYPES_H_
 
 #include "base/time/time.h"
 #include "url/gurl.h"
 
@@ skipping 51 matching lines @@
 
   GURL search_url;
   GURL target_url;
   GURL fullpage_interactive_url;
 
   DoodleImage large_image;
   DoodleImage large_cta_image;
   DoodleImage transparent_large_image;
 
   // TODO(treib,fhorschig): Don't expose this? Clients don't care about it.
-  base::Time expiry_date;
+  base::TimeDelta time_to_live;
 
   // Copying and assignment allowed.
 };
 
 }  // namespace doodle
 
 #endif  // COMPONENTS_DOODLE_DOODLE_TYPES_H_