Add a way to send the resource percentage signal to the RC.

components/offline_pages/core/background/offliner_stub.cc

Index: components/offline_pages/core/background/offliner_stub.cc
diff --git a/components/offline_pages/core/background/offliner_stub.cc b/components/offline_pages/core/background/offliner_stub.cc
index 58b80a159286601b889932e8cecc78754d00f547..bdf99f1778960db1f7385508db87dc2ea3ef0249 100644
--- a/components/offline_pages/core/background/offliner_stub.cc
+++ b/components/offline_pages/core/background/offliner_stub.cc
@@ -60,4 +60,8 @@ bool OfflinerStub::HandleTimeout(int64_t request_id) {
   return false;
 }
 
+void OfflinerStub::ObserveResourceTracking(ResourceDataType type,
+                                           int64_t started_count,
+                                           int64_t completed_count) {}
+
 }  // namespace offline_pages