Extract subpixel offsets from composited layer transforms when possible.

cc/trees/property_tree_builder.cc

Index: cc/trees/property_tree_builder.cc
diff --git a/cc/trees/property_tree_builder.cc b/cc/trees/property_tree_builder.cc
index befc6a514caddb485965811fa0c0d3e08bfd8a10..dd40d2f520f132c22f1157687625992f477ec880 100644
--- a/cc/trees/property_tree_builder.cc
+++ b/cc/trees/property_tree_builder.cc
@@ -239,6 +239,9 @@ bool AddTransformNodeIfNeeded(
   const bool has_potentially_animated_transform =
       layer->HasPotentiallyRunningTransformAnimation();
 
+    LOG(ERROR) << "AddTransformNodeIfNeeded: " << layer;
+
+
   // A transform node is needed even for a finished animation, since differences
   // in the timing of animation state updates can mean that an animation that's
   // in the Finished state at tree-building time on the main thread is still in
@@ -322,6 +325,8 @@ bool AddTransformNodeIfNeeded(
     }
     layer->set_offset_to_transform_parent(source_offset + source_to_parent +
                                           local_offset);
+    LOG(ERROR) << "subpixel offset: " << layer->subpixel_offset_.ToString();
+    LOG(ERROR) << "set_offset_to_transform_parent: " << layer << ": " << layer->offset_to_transform_parent().ToString() << ": " << layer->transform().To2dTranslation().ToString();
     layer->set_should_flatten_transform_from_property_tree(
         data_from_ancestor.should_flatten);
     layer->SetTransformTreeIndex(parent_index);