Keep track of fixed positioning in accessibility tree.

content/renderer/accessibility/render_accessibility_impl.cc

Index: content/renderer/accessibility/render_accessibility_impl.cc
diff --git a/content/renderer/accessibility/render_accessibility_impl.cc b/content/renderer/accessibility/render_accessibility_impl.cc
index 059bd19fbeb08a10e3fcd5acaa87d96eb2f05a3d..f533be0a55b7634c6e2e0f37e0c82e06acb35829 100644
--- a/content/renderer/accessibility/render_accessibility_impl.cc
+++ b/content/renderer/accessibility/render_accessibility_impl.cc
@@ -427,6 +427,7 @@ void RenderAccessibilityImpl::SendPendingAccessibilityEvents() {
       dst.offset_container_id = src.offset_container_id;
       dst.bounds = src.location;
       dst.transform.reset(nullptr);
+      dst.is_fixed_positioned = src.is_fixed_positioned;
       if (src.transform)
         dst.transform.reset(new gfx::Transform(*src.transform));
     }
@@ -474,11 +475,13 @@ void RenderAccessibilityImpl::SendLocationChanges() {
     WebAXObject offset_container;
     WebFloatRect bounds_in_container;
     SkMatrix44 container_transform;
+    bool is_fixed_positioned;
     obj.GetRelativeBounds(offset_container, bounds_in_container,
-                          container_transform);
+                          container_transform, is_fixed_positioned);
     ui::AXRelativeBounds new_location;
     new_location.offset_container_id = offset_container.AxID();
     new_location.bounds = bounds_in_container;
+    new_location.is_fixed_positioned = is_fixed_positioned;
     if (!container_transform.isIdentity())
       new_location.transform = base::WrapUnique(
           new gfx::Transform(container_transform));