Keep track of fixed positioning in accessibility tree.

ui/accessibility/ax_relative_bounds.cc

Index: ui/accessibility/ax_relative_bounds.cc
diff --git a/ui/accessibility/ax_relative_bounds.cc b/ui/accessibility/ax_relative_bounds.cc
index 322a0680fc3e3d64eca1c77725be61fdf56e508a..4984d261c19b67f9949032fc42c304d8118b0a2b 100644
--- a/ui/accessibility/ax_relative_bounds.cc
+++ b/ui/accessibility/ax_relative_bounds.cc
@@ -12,8 +12,7 @@ using base::IntToString;
 namespace ui {
 
 AXRelativeBounds::AXRelativeBounds()
-    : offset_container_id(-1) {
-}
+    : offset_container_id(-1), is_fixed_positioned(false) {}
 
 AXRelativeBounds::~AXRelativeBounds() {
 }
@@ -23,6 +22,7 @@ AXRelativeBounds::AXRelativeBounds(const AXRelativeBounds& other) {
   bounds = other.bounds;
   if (other.transform)
     transform.reset(new gfx::Transform(*other.transform));
+  is_fixed_positioned = other.is_fixed_positioned;
 }
 
 AXRelativeBounds& AXRelativeBounds::operator=(AXRelativeBounds other) {
@@ -30,6 +30,7 @@ AXRelativeBounds& AXRelativeBounds::operator=(AXRelativeBounds other) {
   bounds = other.bounds;
   if (other.transform)
     transform.reset(new gfx::Transform(*other.transform));
+  is_fixed_positioned = other.is_fixed_positioned;
   return *this;
 }
 
@@ -38,6 +39,8 @@ bool AXRelativeBounds::operator==(const AXRelativeBounds& other) {
     return false;
   if (bounds != other.bounds)
     return false;
+  if (is_fixed_positioned != other.is_fixed_positioned)
+    return false;
   if (!transform && !other.transform)
     return true;
   if ((transform && !other.transform) || (!transform && other.transform))
@@ -63,6 +66,9 @@ std::string AXRelativeBounds::ToString() const {
   if (transform && !transform->IsIdentity())
     result += " transform=" + transform->ToString();
 
+  if (is_fixed_positioned)
+    result += " is_fixed_positioned";
+
   return result;
 }