cc: Move more functionality from host to LayerTreeImpl

cc/layer_tree_impl.cc

Index: cc/layer_tree_impl.cc
diff --git a/cc/layer_tree_impl.cc b/cc/layer_tree_impl.cc
index 5abe6e4656dea98f452d71ede8b92c978f6e2c12..e07fa03d2b0c43b7fbfa2ee2e2c119a55c2059c5 100644
--- a/cc/layer_tree_impl.cc
+++ b/cc/layer_tree_impl.cc
@@ -17,6 +17,8 @@ LayerTreeImpl::LayerTreeImpl(LayerTreeHostImpl* layer_tree_host_impl)
     , hud_layer_(0)
     , root_scroll_layer_(0)
     , currently_scrolling_layer_(0)
+    , background_color_(0)
+    , has_transparent_background_(false)
     , scrolling_layer_id_from_previous_tree_(0) {
 }