Draggable peeking/fullscreen launcher with transparent background.

ash/shelf/shelf.cc

Index: ash/shelf/shelf.cc
diff --git a/ash/shelf/shelf.cc b/ash/shelf/shelf.cc
index 8068204d5fecafd76e0a967a925eae1679e7ab9e..f28a25bd1b9df9d55c73351fa3632b42530c2a0e 100644
--- a/ash/shelf/shelf.cc
+++ b/ash/shelf/shelf.cc
@@ -319,6 +319,10 @@ ShelfView* Shelf::GetShelfViewForTesting() {
   return shelf_widget_->shelf_view_for_testing();
 }
 
+void Shelf::OnAppListIsActive(bool hideBackground) {
+  shelf_layout_manager()->OnAppListIsActive(hideBackground);
+}
+
 void Shelf::WillDeleteShelfLayoutManager() {
   if (Shell::GetAshConfig() == Config::MASH) {
     // TODO(sky): this should be removed once Shell is used everywhere.