overview: Fix swiping on no recents label.

Test: manual
Bug: 1002726
Change-Id: I0809b87c4a61601aa5b9a80e716f8b2fc77c57d0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1797111Reviewed-by: Avery Musbach <amusbach@chromium.org>
Commit-Queue: Sammie Quon <sammiequon@chromium.org>
Cr-Commit-Position: refs/heads/master@{#695690}

ash/wm/overview/overview_session.cc

@@ -628,7 +628,7 @@ OverviewSession::UpdateGridAtLocationYPositionAndOpacity(
       callback.Run(settings.get());
     }
     window->SetTransform(
-        gfx::Transform(1.f, 0.f, 0.f, 1.f, 0.f, static_cast<float>(new_y)));
+        gfx::Transform(1.f, 0.f, 0.f, 1.f, 0.f, static_cast<float>(-new_y)));
     window->layer()->SetOpacity(opacity);
     return settings;
   }