cc: Record statistics about approximated content.

cc/trees/layer_tree_host_impl.cc

Index: cc/trees/layer_tree_host_impl.cc
diff --git a/cc/trees/layer_tree_host_impl.cc b/cc/trees/layer_tree_host_impl.cc
index 108969dedc6d9ba0d18887361e174964473b85a6..6d618e4012eae7b1fedf8a42cb3787382f06876d 100644
--- a/cc/trees/layer_tree_host_impl.cc
+++ b/cc/trees/layer_tree_host_impl.cc
@@ -861,6 +861,11 @@ DrawSwapReadbackResult::DrawResult LayerTreeHostImpl::CalculateRenderPasses(
       ++layers_drawn;
     }
 
+    rendering_stats_instrumentation_->AddVisibleContentArea(
+        append_quads_data.visible_content_area);
+    rendering_stats_instrumentation_->AddApproximatedVisibleContentArea(
+        append_quads_data.approximated_visible_content_area);
+
     if (append_quads_data.num_missing_tiles) {
       bool layer_has_animating_transform =
           it->screen_space_transform_is_animating() ||