Implemented the "aria-current" state on Windows.

ui/accessibility/ax_enums.idl

Index: ui/accessibility/ax_enums.idl
diff --git a/ui/accessibility/ax_enums.idl b/ui/accessibility/ax_enums.idl
index e8299f84099a0d802d3d4aa227eb7631e3cebb3a..f215eac5d27f7c0d4d3f24033c992c515bd7e045 100644
--- a/ui/accessibility/ax_enums.idl
+++ b/ui/accessibility/ax_enums.idl
@@ -317,6 +317,10 @@
     // In the case of AX_ROLE_COLOR_WELL, specifies the selected color.
     color_value,
 
+    // Indicates the element that represents the current item within a container
+    // or set of related elements.
+    aria_current,
+
     // Text attributes.
 
     // Foreground and background color in RGBA.
@@ -425,6 +429,16 @@
     text_style_line_through = 8
   };
 
+  [cpp_enum_prefix_override="ax"] enum AXAriaCurrent {
+    aria_current_false,
+    aria_current_true,
+    aria_current_page,
+    aria_current_step,
+    aria_current_location,
+    aria_current_date,
+    aria_current_time
+  };
+
   [cpp_enum_prefix_override="ax"] enum AXInvalidState {
     invalid_state_false,
     invalid_state_true,