[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..98da421af2f4844c2fda45208c8e0acf3d0e9f05 100644
--- a/components/offline_pages/core/prefetch/prefetch_service_impl.cc
+++ b/components/offline_pages/core/prefetch/prefetch_service_impl.cc
@@ -23,6 +23,11 @@ void PrefetchServiceImpl::RemovePrefetchURLsByClientId(
   NOTIMPLEMENTED();
 }
 
+void PrefetchServiceImpl::BeginBackgroundTask(
+    std::unique_ptr<ScopedBackgroundTask> task) {}
+
+void PrefetchServiceImpl::StopBackgroundTask(ScopedBackgroundTask* task) {}
+
 void PrefetchServiceImpl::Shutdown() {}
 
 }  // namespace offline_pages