Added preliminary support for tile rasterization with Ganesh

cc/trees/layer_tree_settings.h

Index: cc/trees/layer_tree_settings.h
diff --git a/cc/trees/layer_tree_settings.h b/cc/trees/layer_tree_settings.h
index e88f8820768f0c9e968c4ff818caaf4d4f9b9beb..215b8bd1efd97415fded1e083854f7b73515e6bd 100644
--- a/cc/trees/layer_tree_settings.h
+++ b/cc/trees/layer_tree_settings.h
@@ -63,6 +63,7 @@ class CC_EXPORT LayerTreeSettings {
   size_t max_unused_resource_memory_percentage;
   int highp_threshold_min;
   bool force_direct_layer_drawing;  // With Skia GPU backend.
+  bool gpu_rasterizing;             // GPU tile rasterization.
   bool strict_layer_property_change_checking;
   bool use_map_image;
   bool ignore_root_layer_flings;