cc: Remove EnsureRenderSurfaceLayerList, do UpdateDrawProps when needed.

cc/trees/layer_tree_impl.cc

Index: cc/trees/layer_tree_impl.cc
diff --git a/cc/trees/layer_tree_impl.cc b/cc/trees/layer_tree_impl.cc
index 9932a33be03d59d47c6ea65ad437c8a46b4e76a6..bbb39e1cb2fe43525af8bd7dc44f63f9aa200615 100644
--- a/cc/trees/layer_tree_impl.cc
+++ b/cc/trees/layer_tree_impl.cc
@@ -438,16 +438,16 @@ void LayerTreeImpl::ClearViewportLayers() {
   outer_viewport_scroll_layer_ = NULL;
 }
 
-void LayerTreeImpl::UpdateDrawProperties() {
-  needs_update_draw_properties_ = false;
-  render_surface_layer_list_.clear();
-
+bool LayerTreeImpl::UpdateDrawProperties() {
   // For max_texture_size.
   if (!layer_tree_host_impl_->renderer())
-    return;
+    return false;

[Ian Vollick, 2014/06/12 15:55:03]

Why don't we want to clear the RSLL when we bail early?

[danakj, 2014/06/12 16:03:58]

The flag is still dirty so the values are still old. I'd rather this method do
nothing if it returns false.

[Ian Vollick, 2014/06/12 16:22:19]

sg

 
   if (!root_layer())
-    return;
+    return false;
+
+  needs_update_draw_properties_ = false;
+  render_surface_layer_list_.clear();
 
   {
     TRACE_EVENT2("cc",
@@ -510,6 +510,7 @@ void LayerTreeImpl::UpdateDrawProperties() {
 
   DCHECK(!needs_update_draw_properties_) <<
       "CalcDrawProperties should not set_needs_update_draw_properties()";
+  return true;
 }
 
 const LayerImplList& LayerTreeImpl::RenderSurfaceLayerList() const {
@@ -1229,6 +1230,10 @@ struct HitTestVisibleScrollableOrTouchableFunctor {
 
 LayerImpl* LayerTreeImpl::FindLayerThatIsHitByPoint(
     const gfx::PointF& screen_space_point) {
+  if (!root_layer())
+    return NULL;
+  if (needs_update_draw_properties_ && !UpdateDrawProperties())

[enne (OOO), 2014/06/11 21:28:43]

What about having UpdateDrawProperties early out with "return true" if
!needs_update_draw_properties? That'll make this condition shorter and will get
us an early out if anybody calls UpdateDrawProperties extra.

[danakj, 2014/06/11 21:41:19]

Ya, I didn't do that only cuz I'm scared it might make bugs I don't trust our
dirty state tracking I guess, but that's a poor reason. I'll do it.

[danakj, 2014/06/12 18:26:50]

Done.

+    return NULL;
   FindClosestMatchingLayerDataForRecursion data_for_recursion;
   FindClosestMatchingLayer(screen_space_point,
                            root_layer(),
@@ -1268,6 +1273,10 @@ struct FindTouchEventLayerFunctor {
 
 LayerImpl* LayerTreeImpl::FindLayerThatIsHitByPointInTouchHandlerRegion(
     const gfx::PointF& screen_space_point) {
+  if (!root_layer())
+    return NULL;
+  if (needs_update_draw_properties_ && !UpdateDrawProperties())
+    return NULL;
   FindTouchEventLayerFunctor func = {screen_space_point};
   FindClosestMatchingLayerDataForRecursion data_for_recursion;
   FindClosestMatchingLayer(