Associate a scan mode with Physical Web listeners

components/ntp_snippets/physical_web_pages/physical_web_page_suggestions_provider.cc

Index: components/ntp_snippets/physical_web_pages/physical_web_page_suggestions_provider.cc
diff --git a/components/ntp_snippets/physical_web_pages/physical_web_page_suggestions_provider.cc b/components/ntp_snippets/physical_web_pages/physical_web_page_suggestions_provider.cc
index 3f32e9e453f0e8c8cc32a5ff1d8cd4c3ce5f590c..5398b22d65cf5e36eec8c2b99d5574a68736294c 100644
--- a/components/ntp_snippets/physical_web_pages/physical_web_page_suggestions_provider.cc
+++ b/components/ntp_snippets/physical_web_pages/physical_web_page_suggestions_provider.cc
@@ -98,7 +98,8 @@ PhysicalWebPageSuggestionsProvider::PhysicalWebPageSuggestionsProvider(
       physical_web_data_source_(physical_web_data_source),
       pref_service_(pref_service) {
   observer->OnCategoryStatusChanged(this, provided_category_, category_status_);
-  physical_web_data_source_->RegisterListener(this);
+  physical_web_data_source_->RegisterListener(this,
+      physical_web::BACKGROUND_INTERMITTENT);
   // TODO(vitaliii): Rewrite initial fetch once crbug.com/667754 is resolved.
   FetchPhysicalWebPages();
 }