Draggable peeking/fullscreen launcher with transparent background.

ash/shelf/shelf_layout_manager.h

Index: ash/shelf/shelf_layout_manager.h
diff --git a/ash/shelf/shelf_layout_manager.h b/ash/shelf/shelf_layout_manager.h
index b7e68fabc55c4ff922638263917f41662a49cc17..5e3ca74df07a18da75f520a01b8d7787e44770bd 100644
--- a/ash/shelf/shelf_layout_manager.h
+++ b/ash/shelf/shelf_layout_manager.h
@@ -64,7 +64,6 @@ class ASH_EXPORT ShelfLayoutManager
 
   // Clears internal data for shutdown process.
   void PrepareForShutdown();
-
   // Returns whether the shelf and its contents (shelf, status) are visible
   // on the screen.
   bool IsVisible() const;
@@ -138,6 +137,8 @@ class ASH_EXPORT ShelfLayoutManager
   void OnPinnedStateChanged(aura::Window* pinned_window) override;
   void OnVirtualKeyboardStateChanged(bool activated,
                                      aura::Window* root_window) override;
+  void OnAppListVisibilityChanged(bool shown,
+                                  aura::Window* root_window) override;
 
   // Overridden from wm::ActivationChangeObserver:
   void OnWindowActivated(ActivationReason reason,
@@ -313,6 +314,10 @@ class ASH_EXPORT ShelfLayoutManager
   // Do any windows overlap the shelf? This is maintained by WorkspaceManager.
   bool window_overlaps_shelf_;
 
+  // Is the AppList visible? This is maintained by
+  // OnAppListVisibilityChanged.
+  bool is_app_list_visible_ = false;
+
   base::OneShotTimer auto_hide_timer_;
 
   // Whether the mouse was over the shelf when the auto hide timer started.