Draggable peeking/fullscreen launcher with transparent background.

ash/shelf/shelf.h

Index: ash/shelf/shelf.h
diff --git a/ash/shelf/shelf.h b/ash/shelf/shelf.h
index af21bc46767b898b04cd986f14720da213d0bb4c..1e4c13c8d6b1faafbcc415a32297eaaabb5730d3 100644
--- a/ash/shelf/shelf.h
+++ b/ash/shelf/shelf.h
@@ -135,6 +135,10 @@ class ASH_EXPORT Shelf : public ShelfLayoutManagerObserver {
   ShelfLockingManager* GetShelfLockingManagerForTesting();
   ShelfView* GetShelfViewForTesting();
 
+  // Called when the app list is active in order to restrict the background
+  // behavior.

[vadimt, 2017/05/26 17:58:55]

Nit: for OnXXX methods, you don't need to specify why they are called. Only
when.
And rename param to something like is_active. Note: not isActive.

[newcomer, 2017/05/26 23:20:21]

Done.

+  void OnAppListIsActive(bool hideBackground);

[xiyuan, 2017/05/26 18:27:31]

hideBackground -> hide_background

It is strange that the name looks irrelevant to applist active state. Should it
be called something like |active|? 

[newcomer, 2017/05/26 23:20:21]

Renamed to is_active .

+
  protected:
   // ShelfLayoutManagerObserver:
   void WillDeleteShelfLayoutManager() override;