Draggable peeking/fullscreen launcher with transparent background.

ash/shelf/wm_shelf.cc

Index: ash/shelf/wm_shelf.cc
diff --git a/ash/shelf/wm_shelf.cc b/ash/shelf/wm_shelf.cc
index c47d951f8070344054623d5cafd6224b72795e8e..77ca939b33aac54079fa01f44c7cdc59313c93ba 100644
--- a/ash/shelf/wm_shelf.cc
+++ b/ash/shelf/wm_shelf.cc
@@ -219,6 +219,10 @@ ShelfBackgroundType WmShelf::GetBackgroundType() const {
   return shelf_widget_->GetBackgroundType();
 }
 
+void WmShelf::AppListIsActive(bool active) {
+  shelf_layout_manager()->AppListIsActive(active);
+}
+
 void WmShelf::UpdateVisibilityState() {
   if (shelf_layout_manager_)
     shelf_layout_manager_->UpdateVisibilityState();
@@ -357,6 +361,7 @@ void WmShelf::OnBackgroundUpdated(ShelfBackgroundType background_type,
                                   AnimationChangeType change_type) {
   if (background_type == GetBackgroundType())
     return;
+
   for (auto& observer : observers_)
     observer.OnBackgroundTypeChanged(background_type, change_type);
 }