Draggable peeking/fullscreen launcher with transparent background.

ash/app_list/app_list_presenter_delegate.cc

Index: ash/app_list/app_list_presenter_delegate.cc
diff --git a/ash/app_list/app_list_presenter_delegate.cc b/ash/app_list/app_list_presenter_delegate.cc
index b458f5c6f6d47e82139d080f2cf304111d1b3fe4..9100f55842030f701bd4f7102dc217bb2f9bbeaa 100644
--- a/ash/app_list/app_list_presenter_delegate.cc
+++ b/ash/app_list/app_list_presenter_delegate.cc
@@ -114,6 +114,11 @@ void AppListPresenterDelegate::Init(app_list::AppListView* view,
   WmShelf* shelf = WmShelf::ForWindow(root_window);
   shelf->AddObserver(this);
 
+  // Notify the shelf that the app list is active so the backgrounds do not
+  // overlap.
+  if (app_list::features::IsFullscreenAppListEnabled())
+    shelf->AppListIsActive(true);
+
   // By setting us as DnD recipient, the app list knows that we can
   // handle items.
   view->SetDragAndDropHostOfCurrentAppList(
@@ -142,6 +147,11 @@ void AppListPresenterDelegate::OnDismissed() {
   AppListButton* app_list_button = shelf->shelf_widget()->GetAppListButton();
   if (app_list_button)
     app_list_button->OnAppListDismissed();
+
+  if(app_list::features::IsFullscreenAppListEnabled())
+    // Notify the shelf that the app list is being dismissed so it can
+    // re-enable its transparent background.
+    shelf->AppListIsActive(false);

[vadimt, 2017/05/22 23:36:56]

Just asking: isn't OnShown a counterpart of OnDismissed, and should we move the
AppListIsActive(true) to OnShown?

[newcomer, 2017/05/25 23:10:50]

You're correct! I put it in OnShown.

 }
 
 void AppListPresenterDelegate::UpdateBounds() {