Add GrabWindowSnapshotAsync tests

ui/snapshot/snapshot_android.cc

Index: ui/snapshot/snapshot_android.cc
diff --git a/ui/snapshot/snapshot_android.cc b/ui/snapshot/snapshot_android.cc
index 3ae0be71283693a48a53414b0e6b2ee844e041ee..83c5efe0ffc372a234ceec4532db851b4e04b5b7 100644
--- a/ui/snapshot/snapshot_android.cc
+++ b/ui/snapshot/snapshot_android.cc
@@ -33,7 +33,7 @@ bool GrabWindowSnapshot(gfx::NativeWindow window,
       scaled_bounds.height(), png_representation);
 }
 
-SNAPSHOT_EXPORT void GrabWindowSnapshotAsync(
+void GrabWindowSnapshotAndScaleAsync(
     gfx::NativeWindow window,
     const gfx::Rect& snapshot_bounds,
     const gfx::Size& target_size,
@@ -42,4 +42,12 @@ SNAPSHOT_EXPORT void GrabWindowSnapshotAsync(
   NOTIMPLEMENTED();
 }
 
+void GrabWindowSnapshotAsync(
+    gfx::NativeWindow window,
+    const gfx::Rect& source_rect,
+    scoped_refptr<base::TaskRunner> background_task_runner,
+    const GrabWindowSnapshotAsyncCallback& callback) {
+  NOTIMPLEMENTED();
+}
+
 }  // namespace ui