[NTP::Downloads] Do not show old downloads.

chrome/browser/ntp_snippets/download_suggestions_provider.h

Index: chrome/browser/ntp_snippets/download_suggestions_provider.h
diff --git a/chrome/browser/ntp_snippets/download_suggestions_provider.h b/chrome/browser/ntp_snippets/download_suggestions_provider.h
index 59bf356f557328a90abd3ced220aa8b826f48c8b..9cac825d2e4a652f04f5e5fe81fd32d855c7c055 100644
--- a/chrome/browser/ntp_snippets/download_suggestions_provider.h
+++ b/chrome/browser/ntp_snippets/download_suggestions_provider.h
@@ -28,6 +28,10 @@ namespace offline_pages {
 struct OfflinePageItem;
 }
 
+namespace base {
+class Clock;
+}
+
 // Provides download content suggestions from the offline pages model and the
 // download manager (obtaining the data through DownloadManager and each
 // DownloadItem). Offline page related downloads are referred to as offline page
@@ -46,7 +50,8 @@ class DownloadSuggestionsProvider
       offline_pages::OfflinePageModel* offline_page_model,
       content::DownloadManager* download_manager,
       DownloadHistory* download_history,
-      PrefService* pref_service);
+      PrefService* pref_service,
+      std::unique_ptr<base::Clock> clock);
   ~DownloadSuggestionsProvider() override;
 
   // ContentSuggestionsProvider implementation.
@@ -136,6 +141,10 @@ class DownloadSuggestionsProvider
   ntp_snippets::ContentSuggestion ConvertDownloadItem(
       const content::DownloadItem& download_item) const;
 
+  // Returns true if a download published time is considered too old for the
+  // download to be shown.
+  bool IsDownloadOutdated(const base::Time& published_time);
+
   // Adds |item| to the internal asset download cache if all of the following
   // holds:
   // - the download is completed;
@@ -205,8 +214,8 @@ class DownloadSuggestionsProvider
   offline_pages::OfflinePageModel* offline_page_model_;
   content::DownloadManager* download_manager_;
   DownloadHistory* download_history_;
-
   PrefService* pref_service_;
+  std::unique_ptr<base::Clock> clock_;
 
   // Cached offline page downloads. If there are not enough asset downloads, all
   // of these could be shown (they are the most recently visited, not dismissed