[remote suggestions] Attach the fetch time to RemoteSnippets, ContentSnippets and SnippetArticle

components/ntp_snippets/remote/remote_suggestion.h

Index: components/ntp_snippets/remote/remote_suggestion.h
diff --git a/components/ntp_snippets/remote/remote_suggestion.h b/components/ntp_snippets/remote/remote_suggestion.h
index c08e7ecfd2678bc53ac3edb7eaf346471b2c3586..b558e83dfd10051246c710f75d123ffb6cbb4dab 100644
--- a/components/ntp_snippets/remote/remote_suggestion.h
+++ b/components/ntp_snippets/remote/remote_suggestion.h
@@ -38,14 +38,16 @@ class RemoteSuggestion {
   // suggestion. The keys in the dictionary are expected to be the same as the
   // property name, with exceptions documented in the property comment.
   static std::unique_ptr<RemoteSuggestion> CreateFromChromeReaderDictionary(
-      const base::DictionaryValue& dict);
+      const base::DictionaryValue& dict,
+      const base::Time& fetch_time);
 
   // Creates a RemoteSuggestion from a dictionary, as returned by Chrome Content
   // Suggestions. Returns a null pointer if the dictionary doesn't correspond to
   // a valid suggestion. Maps field names to Chrome Reader field names.
   static std::unique_ptr<RemoteSuggestion>
   CreateFromContentSuggestionsDictionary(const base::DictionaryValue& dict,
-                                         int remote_category_id);
+                                         int remote_category_id,
+                                         const base::Time& fetch_time);
 
   // Creates an RemoteSuggestion from a protocol buffer. Returns a null pointer
   // if the protocol buffer doesn't correspond to a valid suggestion.
@@ -63,6 +65,7 @@ class RemoteSuggestion {
   // Creates a protocol buffer corresponding to this suggestion, for persisting.
   SnippetProto ToProto() const;
 
+  // TODO(markusheintz): Move this method to the ContentSuggestion class.

[Marc Treib, 2017/02/10 16:16:56]

No, this belongs here IMO. The general ContentSuggestion class shouldn't know
about the provider-specific suggestion types.

[markusheintz_, 2017/02/13 09:59:55]

I'll remove the TODO. Not feeling strongly about it.

   // Coverts to general content suggestion form
   ContentSuggestion ToContentSuggestion(Category category) const;
 
@@ -120,6 +123,8 @@ class RemoteSuggestion {
   // CategoryFactory::FromRemoteCategory.
   int remote_category_id() const { return remote_category_id_; }
 
+  base::Time fetch_time() const { return fetch_time_; }
+
   // Public for testing.
   static base::Time TimeFromJsonString(const std::string& timestamp_str);
   static std::string TimeToJsonString(const base::Time& time);
@@ -152,6 +157,9 @@ class RemoteSuggestion {
   bool should_notify_;
   base::Time notification_deadline_;
 
+  // The time when the remote suggestions was fetched from the server.
+  base::Time fetch_time_;
+
   DISALLOW_COPY_AND_ASSIGN(RemoteSuggestion);
 };