Keeping track of descendants that draw content instead of recalcualting

cc/trees/occlusion_tracker_unittest.cc

Index: cc/trees/occlusion_tracker_unittest.cc
diff --git a/cc/trees/occlusion_tracker_unittest.cc b/cc/trees/occlusion_tracker_unittest.cc
index 1a6529bc557f1dfeaf8c330bd89e6eb8747d6311..e6464a254dcd8b82f20b42161df255ac94458d42 100644
--- a/cc/trees/occlusion_tracker_unittest.cc
+++ b/cc/trees/occlusion_tracker_unittest.cc
@@ -133,6 +133,8 @@ struct OcclusionTrackerTestMainThreadTypes {
   }
 
   static void DestroyLayer(LayerPtrType* layer) { *layer = NULL; }
+
+  static void RecursiveUpdateNumChildren(LayerType* layerType) {}
 };
 
 struct OcclusionTrackerTestImplThreadTypes {
@@ -162,6 +164,10 @@ struct OcclusionTrackerTestImplThreadTypes {
   }
 
   static void DestroyLayer(LayerPtrType* layer) { layer->reset(); }
+
+  static void RecursiveUpdateNumChildren(LayerType* layer) {
+    FakeLayerTreeHostImpl::RecursiveUpdateNumChildren(layer);
+  }
 };
 
 int OcclusionTrackerTestImplThreadTypes::next_layer_impl_id = 1;
@@ -304,6 +310,7 @@ template <typename Types> class OcclusionTrackerTest : public testing::Test {
     DCHECK(root == root_.get());
     DCHECK(!root->render_surface());
 
+    Types::RecursiveUpdateNumChildren(root);
     LayerTreeHostCommon::CalcDrawPropsImplInputsForTesting inputs(
         root, root->bounds(), &render_surface_layer_list_impl_);
     inputs.can_adjust_raster_scales = true;