[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 012a024bb7e61e82394faffc616290216b300472..ec81611f397807802fc44d407be27ebd1f1b1430 100644
--- a/chrome/browser/ntp_snippets/content_suggestions_service_factory.cc
+++ b/chrome/browser/ntp_snippets/content_suggestions_service_factory.cc
@@ -61,6 +61,7 @@
 #include "chrome/browser/android/chrome_feature_list.h"
 #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/offline_page_suggestions_observer.h"
 #include "chrome/browser/android/offline_pages/request_coordinator_factory.h"
 #include "chrome/browser/download/download_history.h"
 #include "chrome/browser/download/download_service.h"
@@ -362,6 +363,12 @@ KeyedService* ContentSuggestionsServiceFactory::BuildServiceInstanceFor(
         show_asset_downloads ? download_manager : nullptr, download_history,
         service, pref_service);
   }
+
+  if (offline_pages::IsPrefetchingOfflinePagesEnabled()) {
+    offline_pages::OfflinePageSuggestionsObserver::
+        ObserveContentSuggestionsService(profile, offline_page_model, service);

[carlosk, 2017/04/11 17:31:36]

How about renaming the Observer* method to MaybeObserve* and moving the feature
check inside it? I think the logic deciding if an observer should observe or not
should be closer to the observer (and not the observed).

[dewittj, 2017/04/11 21:25:48]

Done, though I don't think the Maybe is strictly necessary.  PTAL.

+  }
+
 #endif  // OS_ANDROID
 
   // |bookmark_model| can be null in tests.