cc : Stop pushing layers from hidden subtrees at commit

cc/layers/layer.h

Index: cc/layers/layer.h
diff --git a/cc/layers/layer.h b/cc/layers/layer.h
index c88721b0fa6e1e82ad3728900e1d3f93b7cc566b..06fee4bcfa21bd8c1a5903c48042b450e356d3ae 100644
--- a/cc/layers/layer.h
+++ b/cc/layers/layer.h
@@ -25,6 +25,7 @@
 #include "cc/layers/layer_collections.h"
 #include "cc/layers/layer_position_constraint.h"
 #include "cc/paint/paint_record.h"
+#include "cc/surfaces/surface_id.h"
 #include "cc/trees/element_id.h"
 #include "cc/trees/mutator_host_client.h"
 #include "cc/trees/property_tree.h"
@@ -313,6 +314,10 @@ class CC_EXPORT Layer : public base::RefCounted<Layer> {
 
   virtual bool IsSnapped();
 
+  virtual bool IsSurfaceLayer() const;

[enne (OOO), 2017/05/19 22:27:05]

I'm not really that keen on virtuals that say what kind of layer a layer is,
because then other code starts depending on it.  I think I'd prefer a pattern
that was either:

(1) Have each surface layer register itself with LTH (like picture layers
register with LayerTreeImpl) and then just iterate through all surface layers on
commit to append surface ids.  Don't worry about hidden vs not and just put all
surface ids in the referenced list.

(2) Have each surface layer register its surface id with LTH whenever it changes
/ gets a new LTH.  Similarly don't worry about hidden vs not.

[jaydasika, 2017/05/23 00:25:14]

(2) done

+
+  virtual const SurfaceId* GetSurfaceId() const;
+
   virtual void PushPropertiesTo(LayerImpl* layer);
 
   LayerTreeHost* GetLayerTreeHostForTesting() const { return layer_tree_host_; }
@@ -377,6 +382,10 @@ class CC_EXPORT Layer : public base::RefCounted<Layer> {
     return should_flatten_transform_from_property_tree_;
   }
 
+  void SetIsHidden(bool is_hidden);
+
+  bool is_hidden() const { return is_hidden_; }
+
   const gfx::Rect& visible_layer_rect_for_testing() const {
     return visible_layer_rect_;
   }
@@ -613,6 +622,7 @@ class CC_EXPORT Layer : public base::RefCounted<Layer> {
   gfx::Vector2dF offset_to_transform_parent_;
   bool should_flatten_transform_from_property_tree_ : 1;
   bool draws_content_ : 1;
+  bool is_hidden_ : 1;
   bool use_local_transform_for_backface_visibility_ : 1;
   bool should_check_backface_visibility_ : 1;
   bool force_render_surface_for_testing_ : 1;