cc: Add a flag to layers that returns true if the layer is in RSLL.

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 1014a3f8c5c16446a1752579be7d0061ceddec97..34d51dd05534f18aeb12129120bc19777296756f 100644
--- a/cc/trees/layer_tree_impl.cc
+++ b/cc/trees/layer_tree_impl.cc
@@ -97,7 +97,9 @@ LayerTreeImpl::LayerTreeImpl(LayerTreeHostImpl* layer_tree_host_impl)
       viewport_size_invalid_(false),
       needs_update_draw_properties_(true),
       needs_full_tree_sync_(true),
-      next_activation_forces_redraw_(false) {}
+      next_activation_forces_redraw_(false),
+      calculate_draw_properties_count_(0u) {

[vmpstr, 2014/05/02 23:06:27]

There is a SourceAnimationFrameNumber, which happens to be used in unittests
only... I'm somewhat hesitant on relying on that, so I opted in using a separate
count. 

If that's not acceptable, then I will have to do a deeper investigation into
whether the SourceAnimationFrameNumber is really what I want here.

+}
 
 LayerTreeImpl::~LayerTreeImpl() {
   // Need to explicitly clear the tree prior to destroying this so that
@@ -457,6 +459,7 @@ void LayerTreeImpl::UpdateDrawProperties() {
         page_scale_layer_ ? page_scale_layer_ : InnerViewportContainerLayer();
     bool can_render_to_separate_surface =
         !output_surface()->ForcedDrawToSoftwareDevice();
+    ++calculate_draw_properties_count_;
     LayerTreeHostCommon::CalcDrawPropsImplInputs inputs(
         root_layer(),
         DrawViewportSize(),
@@ -490,13 +493,27 @@ void LayerTreeImpl::UpdateDrawProperties() {
          ++it) {
       if (!it.represents_itself())
         continue;
+
       LayerImpl* layer = *it;
+      layer->draw_properties().last_render_surface_list_membership_index =

[vmpstr, 2014/05/02 23:06:27]

I suspect this should happen in LayerTreeHostCommon::CalculateDrawProperties? Is
there a place where we iterate all of the render surface layer list in there? I
found one push back to the list, but the iterate iterates more than just the
list.

[danakj, 2014/05/02 23:09:24]

Right, the output of CalcDrawProps is the RSLL. If you set this on every layer
that you push into the list, then you'll have what you want.

+          calculate_draw_properties_count_;
 
       layer->UpdateTilePriorities();
-      if (layer->mask_layer())
+      if (layer->mask_layer()) {
+        layer->mask_layer()
+            ->draw_properties()
+            .last_render_surface_list_membership_index =
+            calculate_draw_properties_count_;
         layer->mask_layer()->UpdateTilePriorities();
-      if (layer->replica_layer() && layer->replica_layer()->mask_layer())
+      }
+      if (layer->replica_layer() && layer->replica_layer()->mask_layer()) {
+        layer->replica_layer()
+            ->mask_layer()
+            ->draw_properties()
+            .last_render_surface_list_membership_index =
+            calculate_draw_properties_count_;
         layer->replica_layer()->mask_layer()->UpdateTilePriorities();
+      }
     }
   }