[Offline Prefetch] Create a new JobScheduler task to wake up for net activity.

components/offline_pages/core/prefetch/prefetch_service_impl.cc

Index: components/offline_pages/core/prefetch/prefetch_service_impl.cc
diff --git a/components/offline_pages/core/prefetch/prefetch_service_impl.cc b/components/offline_pages/core/prefetch/prefetch_service_impl.cc
index 602b4050e7982f733cd30002ec9d2824972d3e1f..016825f923fce95cf08687e844b213caee27a22a 100644
--- a/components/offline_pages/core/prefetch/prefetch_service_impl.cc
+++ b/components/offline_pages/core/prefetch/prefetch_service_impl.cc
@@ -22,6 +22,10 @@ void PrefetchServiceImpl::RemovePrefetchURLsByClientId(
     const ClientId& client_id) {
   NOTIMPLEMENTED();
 }
+void PrefetchServiceImpl::BeginBackgroundTask(
+    std::unique_ptr<ScopedBackgroundTask> task) {}
+
+void PrefetchServiceImpl::StopBackgroundTask(ScopedBackgroundTask* task) {}
 
 void PrefetchServiceImpl::Shutdown() {}