cc: Remove EnsureRenderSurfaceLayerList, do UpdateDrawProps when needed.

cc/trees/layer_tree_impl.cc

 // Copyright 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "cc/trees/layer_tree_impl.h"
 
 #include <limits>
 #include <set>
 
 #include "base/debug/trace_event.h"
@@ skipping 420 matching lines @@
                                            root_layer_scroll_offset_delegate_,
                                            this));
 }
 
 void LayerTreeImpl::ClearViewportLayers() {
   page_scale_layer_ = NULL;
   inner_viewport_scroll_layer_ = NULL;
   outer_viewport_scroll_layer_ = NULL;
 }
 
-void LayerTreeImpl::UpdateDrawProperties() {
+bool LayerTreeImpl::UpdateDrawProperties() {
+  // For max_texture_size.
+  if (!layer_tree_host_impl_->renderer())
+    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 false;
+
   needs_update_draw_properties_ = false;
   render_surface_layer_list_.clear();
 
-  // For max_texture_size.
-  if (!layer_tree_host_impl_->renderer())
-    return;
-
-  if (!root_layer())
-    return;
-
   {
     TRACE_EVENT2("cc",
                  "LayerTreeImpl::UpdateDrawProperties",
                  "IsActive",
                  IsActiveTree(),
                  "SourceFrameNumber",
                  source_frame_number_);
     LayerImpl* page_scale_layer =
         page_scale_layer_ ? page_scale_layer_ : InnerViewportContainerLayer();
     bool can_render_to_separate_surface =
@@ skipping 41 matching lines @@
 
       if (layer->mask_layer())
         layer->mask_layer()->UpdateTilePriorities();
       if (layer->replica_layer() && layer->replica_layer()->mask_layer())
         layer->replica_layer()->mask_layer()->UpdateTilePriorities();
     }
   }
 
   DCHECK(!needs_update_draw_properties_) <<
       "CalcDrawProperties should not set_needs_update_draw_properties()";
+  return true;
 }
 
 const LayerImplList& LayerTreeImpl::RenderSurfaceLayerList() const {
   // If this assert triggers, then the list is dirty.
   DCHECK(!needs_update_draw_properties_);
   return render_surface_layer_list_;
 }
 
 gfx::Size LayerTreeImpl::ScrollableSize() const {
   LayerImpl* root_scroll_layer = OuterViewportScrollLayer()
@@ skipping 699 matching lines @@
   bool operator()(LayerImpl* layer) const {
     return layer->IsDrawnRenderSurfaceLayerListMember() ||
            ScrollsAnyDrawnRenderSurfaceLayerListMember(layer) ||
            !layer->touch_event_handler_region().IsEmpty() ||
            layer->have_wheel_event_handlers();
   }
 };
 
 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(),
                            HitTestVisibleScrollableOrTouchableFunctor(),
                            &data_for_recursion);
   return data_for_recursion.closest_match;
 }
 
 static bool LayerHasTouchEventHandlersAt(const gfx::PointF& screen_space_point,
                                          LayerImpl* layer_impl) {
@@ skipping 19 matching lines @@
 
 struct FindTouchEventLayerFunctor {
   bool operator()(LayerImpl* layer) const {
     return LayerHasTouchEventHandlersAt(screen_space_point, layer);
   }
   const gfx::PointF screen_space_point;
 };
 
 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(
       screen_space_point, root_layer(), func, &data_for_recursion);
   return data_for_recursion.closest_match;
 }
 
 }  // namespace cc