Keep track of fixed positioning in accessibility tree.

third_party/WebKit/Source/modules/accessibility/AXSpinButton.cpp

Index: third_party/WebKit/Source/modules/accessibility/AXSpinButton.cpp
diff --git a/third_party/WebKit/Source/modules/accessibility/AXSpinButton.cpp b/third_party/WebKit/Source/modules/accessibility/AXSpinButton.cpp
index 1e8e30c5498f4b3248645cbbcb7ce375dcfd654c..c131d7dd5c746859b1386ebde548f6d557aeabb1 100644
--- a/third_party/WebKit/Source/modules/accessibility/AXSpinButton.cpp
+++ b/third_party/WebKit/Source/modules/accessibility/AXSpinButton.cpp
@@ -101,13 +101,14 @@ AXSpinButtonPart* AXSpinButtonPart::Create(AXObjectCacheImpl& ax_object_cache) {
   return new AXSpinButtonPart(ax_object_cache);
 }
 
-void AXSpinButtonPart::GetRelativeBounds(
-    AXObject** out_container,
-    FloatRect& out_bounds_in_container,
-    SkMatrix44& out_container_transform) const {
+void AXSpinButtonPart::GetRelativeBounds(AXObject** out_container,
+                                         FloatRect& out_bounds_in_container,
+                                         SkMatrix44& out_container_transform,
+                                         bool& out_is_fixed_positioned) const {
   *out_container = nullptr;
   out_bounds_in_container = FloatRect();
   out_container_transform.setIdentity();
+  out_is_fixed_positioned = false;

[aboxhall, 2017/06/30 06:07:41]

Is there some reason we couldn't make is_fixed_positioned part of the
WebAXObject API instead of attaching it to this method?

[dmazzoni, 2017/07/06 07:20:22]

I don't want to do that in the WebAXObject API because is_fixed_positioned
is a critical piece of information that's intertwined with the rest of the
bounds info, so I want to force callers to fetch all of them together.

How about this, though - I added a new protected method
GetSimpleRelativeBounds that can be overridden by this
class and two others that have to return their own bounds but
have no use for transforms or fixed positioning. Does that
help readability?

 
   if (!ParentObject())
     return;
@@ -115,7 +116,8 @@ void AXSpinButtonPart::GetRelativeBounds(
   // FIXME: This logic should exist in the layout tree or elsewhere, but there
   // is no relationship that exists that can be queried.
   ParentObject()->GetRelativeBounds(out_container, out_bounds_in_container,
-                                    out_container_transform);
+                                    out_container_transform,
+                                    out_is_fixed_positioned);
   out_bounds_in_container = FloatRect(0, 0, out_bounds_in_container.Width(),
                                       out_bounds_in_container.Height());
   if (is_incrementor_) {