Revert of 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 1a8256bdf1a64ce3315f46daa82ff5f4271eb67c..8cf8a5f9f32a2d4384cea5023f23e4af8335dd92 100644
--- a/ui/gfx/native_widget_types.h
+++ b/ui/gfx/native_widget_types.h
@@ -105,13 +105,6 @@
 }
 #endif
 class SkBitmap;
-
-#if defined(USE_X11) && !defined(OS_CHROMEOS)
-extern "C" {
-struct _AtkObject;
-typedef struct _AtkObject AtkObject;
-}
-#endif
 
 namespace gfx {
 
@@ -171,11 +164,7 @@
 #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.