Make apps grid view scroll vertically in experimental app list.

ash/wm/app_list_controller.cc

Index: ash/wm/app_list_controller.cc
diff --git a/ash/wm/app_list_controller.cc b/ash/wm/app_list_controller.cc
index 7e60edc5bbdf8c71f2ab4061ddf9d28b8a0b68cc..515930507524e271db77b1229ca0f4c2a70ea10a 100644
--- a/ash/wm/app_list_controller.cc
+++ b/ash/wm/app_list_controller.cc
@@ -509,7 +509,12 @@ void AppListController::TransitionChanged() {
     const int shift = kMaxOverScrollShift * progress * dir;
 
     gfx::Rect shifted(view_bounds_);
-    shifted.set_x(shifted.x() + shift);
+    // Experimental app list scrolls vertically, so make the overscroll
+    // vertical.
+    if (app_list::switches::IsExperimentalAppListEnabled())
+      shifted.set_y(shifted.y() + shift);
+    else
+      shifted.set_x(shifted.x() + shift);
     widget->SetBounds(shifted);
     should_snap_back_ = true;
   } else if (should_snap_back_) {