Add GrabWindowSnapshotAsync tests

ui/snapshot/snapshot_win.cc

Index: ui/snapshot/snapshot_win.cc
diff --git a/ui/snapshot/snapshot_win.cc b/ui/snapshot/snapshot_win.cc
index fc157bed2d2b586bd43d975cd4fca38b4e1e3616..da9f1ccbd0195ff50ed83ce02a98f045972e1b52 100644
--- a/ui/snapshot/snapshot_win.cc
+++ b/ui/snapshot/snapshot_win.cc
@@ -119,7 +119,7 @@ bool GrabWindowSnapshot(gfx::NativeWindow window_handle,
                                     png_representation);
 }
 
-SNAPSHOT_EXPORT void GrapWindowSnapshotAsync(
+void GrapWindowSnapshotAsync(
     gfx::NativeWindow window,
     const gfx::Rect& snapshot_bounds,
     const gfx::Size& target_size,
@@ -128,6 +128,14 @@ SNAPSHOT_EXPORT void GrapWindowSnapshotAsync(
   NOTIMPLEMENTED();
 }
 
+void GrabWindowSnapshotAsync(
+    gfx::NativeWindow window,
+    const gfx::Rect& source_rect,
+    scoped_refptr<base::TaskRunner> background_task_runner,
+    const GrabWindowSnapshotAsyncCallback& callback) {
+  NOTIMPLEMENTED();
+}
+
 #endif  // !defined(USE_AURA)
 
 }  // namespace ui