cc: Remove map lookup from RenderSurfaceImpl::EffectTreeIndex

cc/trees/layer_tree_host_in_process.cc

Index: cc/trees/layer_tree_host_in_process.cc
diff --git a/cc/trees/layer_tree_host_in_process.cc b/cc/trees/layer_tree_host_in_process.cc
index aac493b0b3a5f71758203bb0c2bf736f917d571b..1f0eab1c21a0057bf87c4b5ca19c9d359912efb9 100644
--- a/cc/trees/layer_tree_host_in_process.cc
+++ b/cc/trees/layer_tree_host_in_process.cc
@@ -600,8 +600,10 @@ static int GetLayersUpdateTimeHistogramBucket(size_t numLayers) {
 }
 
 bool LayerTreeHostInProcess::UpdateLayers() {
-  if (!layer_tree_->root_layer())
+  if (!layer_tree_->root_layer()) {
+    layer_tree_->property_trees()->clear();
     return false;
+  }
   DCHECK(!layer_tree_->root_layer()->parent());
   base::ElapsedTimer timer;