[Doodle] Replace the expiry_date in DoodleConfig by time_to_live

components/doodle/doodle_types.cc

Index: components/doodle/doodle_types.cc
diff --git a/components/doodle/doodle_types.cc b/components/doodle/doodle_types.cc
index c0a1dffde8b2ae79f784ee5f294b67a6c07fe3ac..e74356a51497929652e3281b39095893154e23ea 100644
--- a/components/doodle/doodle_types.cc
+++ b/components/doodle/doodle_types.cc
@@ -16,10 +16,9 @@ bool DoodleImage::operator!=(const DoodleImage& other) const {
 }
 
 bool DoodleConfig::IsEquivalent(const DoodleConfig& other) const {
-  // Note: This compares all fields except for |expiry_date|. The reason is that
-  // |expiry_date| gets computed as "now + time_to_live", so when an identical
-  // config gets re-fetched, the expiry date will generally end up slightly
-  // different.
+  // Note: This compares all fields except for |time_to_live|, which by
+  // definition isn't constant over time, and shouldn't be here in the first
+  // place.

[fhorschig, 2017/03/01 15:40:52]

What do you mean by "shouldn't be here in the first place"?
In this function or in the Config at all?

Maybe it's more important to just say that the TTL is not 
sufficient for distinguishing 2 Doodles.

[Marc Treib, 2017/03/02 09:28:03]

In the config. Made that clear in the comment.
Actually the other way around is more important: Two Doodles with different TTL
(but everything else the same) must still be considered equivalent.
Anyway, I'll send a followup Real Soon Now that'll remove the field from the
config.

   return doodle_type == other.doodle_type && alt_text == other.alt_text &&
          interactive_html == other.interactive_html &&
          search_url == other.search_url && target_url == other.target_url &&