Fix app list search box rendering above app list overlay.

ui/app_list/views/app_list_view.cc

Index: ui/app_list/views/app_list_view.cc
diff --git a/ui/app_list/views/app_list_view.cc b/ui/app_list/views/app_list_view.cc
index f32a48443668e50b4a9bfad3f7fd19de7aa3303b..c78c874b1b963f4c4d89cc2c3064ab1043282ffe 100644
--- a/ui/app_list/views/app_list_view.cc
+++ b/ui/app_list/views/app_list_view.cc
@@ -276,6 +276,16 @@ void AppListView::SetAppListOverlayVisible(bool visible) {
 
   const float kOverlayOpacity = 0.75f;
   overlay_view_->layer()->SetOpacity(visible ? kOverlayOpacity : 0.0f);
+  // Create the illusion that the search box is hidden behind the app list
+  // overlay mask by setting its opacity to the same value, and disabling it.
+  {
+    ui::ScopedLayerAnimationSettings settings(
+        search_box_widget_->GetLayer()->GetAnimator());
+    const float kSearchBoxWidgetOpacity = 0.5f;
+    search_box_widget_->GetLayer()->SetOpacity(visible ? kSearchBoxWidgetOpacity
+                                                       : 1.0f);
+    search_box_view_->SetEnabled(!visible);
+  }
 }
 
 bool AppListView::ShouldCenterWindow() const {