Implement position: sticky updates on compositor

cc/layers/layer_impl.h

Index: cc/layers/layer_impl.h
diff --git a/cc/layers/layer_impl.h b/cc/layers/layer_impl.h
index 0dd2c97ced7f5eb2783ec35f0ba5bfc4933642c3..4511404f31c6fc40b539d044ac5399fff58f396b 100644
--- a/cc/layers/layer_impl.h
+++ b/cc/layers/layer_impl.h
@@ -235,6 +235,14 @@ class CC_EXPORT LayerImpl {
     return use_local_transform_for_backface_visibility_;
   }
 
+  void SetStickyPositionConstraint(
+      const LayerStickyPositionConstraint& constraint) {
+    sticky_position_constraint_ = constraint;
+  }
+  const LayerStickyPositionConstraint& sticky_position_constraint() const {
+    return sticky_position_constraint_;
+  }
+
   void SetShouldCheckBackfaceVisibility(bool should_check_backface_visibility) {
     should_check_backface_visibility_ = should_check_backface_visibility;
   }
@@ -569,6 +577,8 @@ class CC_EXPORT LayerImpl {
   DrawProperties draw_properties_;
   PerformanceProperties<LayerImpl> performance_properties_;
 
+  LayerStickyPositionConstraint sticky_position_constraint_;

[ajuma, 2016/09/08 22:08:53]

Does LayerImpl need to know this? Is it enough for the transform tree to have
it? If you just need this for tests, it can go on LayerImplTestProperties
instead.

[flackr, 2016/09/20 17:08:12]

Done.

+
   std::unique_ptr<base::trace_event::ConvertableToTraceFormat>
       owned_debug_info_;
   base::trace_event::ConvertableToTraceFormat* debug_info_;