[Offline Pages] Set up the initial prefetching service.

chrome/browser/ntp_snippets/content_suggestions_service_factory.cc

Index: chrome/browser/ntp_snippets/content_suggestions_service_factory.cc
diff --git a/chrome/browser/ntp_snippets/content_suggestions_service_factory.cc b/chrome/browser/ntp_snippets/content_suggestions_service_factory.cc
index 29f8045ec0a56653d687f33edf513b10019ab0f2..91aed0d2b2c8905b5e1f51a83d2b4a18f20d47c9 100644
--- a/chrome/browser/ntp_snippets/content_suggestions_service_factory.cc
+++ b/chrome/browser/ntp_snippets/content_suggestions_service_factory.cc
@@ -63,6 +63,7 @@
 #include "chrome/browser/android/ntp/ntp_snippets_launcher.h"
 #include "chrome/browser/android/offline_pages/offline_page_model_factory.h"
 #include "chrome/browser/android/offline_pages/request_coordinator_factory.h"
+#include "chrome/browser/android/offline_pages/suggested_articles_observer.h"
 #include "chrome/browser/download/download_history.h"
 #include "chrome/browser/download/download_service.h"
 #include "chrome/browser/download/download_service_factory.h"
@@ -373,6 +374,9 @@ KeyedService* ContentSuggestionsServiceFactory::BuildServiceInstanceFor(
         show_asset_downloads ? download_manager : nullptr, download_history,
         service, pref_service);
   }
+
+  offline_pages::SuggestedArticlesObserver::ObserveContentSuggestionsService(
+      profile, service);
 #endif  // OS_ANDROID
 
   // |bookmark_model| can be null in tests.