Keeping track of descendants that draw content instead of recalcualting

cc/layers/delegated_renderer_layer.cc

Index: cc/layers/delegated_renderer_layer.cc
diff --git a/cc/layers/delegated_renderer_layer.cc b/cc/layers/delegated_renderer_layer.cc
index c47206172ceedcd205e21525f3d11d3778700d3c..127b1c927eb862ef98e25f4ad3df3f469c577367 100644
--- a/cc/layers/delegated_renderer_layer.cc
+++ b/cc/layers/delegated_renderer_layer.cc
@@ -98,4 +98,14 @@ bool DelegatedRendererLayer::Update(ResourceUpdateQueue* queue,
   return true;
 }
 
+int DelegatedRendererLayer::NumDescendantsThatDrawContent() const {
+  // As per the comment that was originally in
+  // LayerTreeHost::PrecalculateMetaInformation:
+  // Layers with delegated content need to be treated as if they have as
+  // many children as the number of layers they own delegated quads for.
+  // Since we don't know this number right now, we choose one that acts like
+  // infinity for our purposes.
+  return Layer::NumDescendantsThatDrawContent() + 1000;
+}
+
 }  // namespace cc