Resurrect Aura Linux accessibility.

ui/gfx/native_widget_types.h

Index: ui/gfx/native_widget_types.h
diff --git a/ui/gfx/native_widget_types.h b/ui/gfx/native_widget_types.h
index 8cf8a5f9f32a2d4384cea5023f23e4af8335dd92..1a8256bdf1a64ce3315f46daa82ff5f4271eb67c 100644
--- a/ui/gfx/native_widget_types.h
+++ b/ui/gfx/native_widget_types.h
@@ -106,6 +106,13 @@ class ViewAndroid;
 #endif
 class SkBitmap;
 
+#if defined(USE_X11) && !defined(OS_CHROMEOS)
+extern "C" {
+struct _AtkObject;
+typedef struct _AtkObject AtkObject;
+}
+#endif
+
 namespace gfx {
 
 #if defined(USE_AURA)
@@ -164,8 +171,12 @@ typedef cairo_t* NativeDrawingContext;
 #else
 typedef void* NativeDrawingContext;
 #endif  // defined(USE_CAIRO)
+#if defined(USE_X11) && !defined(OS_CHROMEOS)
+typedef AtkObject* NativeViewAccessible;
+#else
 typedef void* NativeViewAccessible;
 #endif
+#endif
 
 // A constant value to indicate that gfx::NativeCursor refers to no cursor.
 #if defined(USE_AURA)