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 6c787574b1fee32c5a681dbc3af8b9205973685a..6e691000e8c9f12d6cf46359adf1c65bd2e77f3a 100644
--- a/ash/app_list/app_list_presenter_delegate.cc
+++ b/ash/app_list/app_list_presenter_delegate.cc
@@ -129,6 +129,14 @@ void AppListPresenterDelegate::OnShown(int64_t display_id) {
       Shelf::ForWindow(root_window)->shelf_widget()->GetAppListButton();
   if (app_list_button)
     app_list_button->OnAppListShown();
+
+  // Notify the shelf that the app list is active so the backgrounds do not
+  // overlap.
+

[xiyuan, 2017/05/30 16:32:33]

nit: get rid of the empty line. And maybe move the comment inside "if" similar
to what we have in OnDismissed().

[newcomer, 2017/05/30 21:37:03]

Done.

+  if (app_list::features::IsFullscreenAppListEnabled()) {
+    Shelf* shelf = Shelf::ForWindow(root_window);
+    shelf->OnAppListIsActive(true);
+  }
 }
 
 void AppListPresenterDelegate::OnDismissed() {
@@ -142,6 +150,11 @@ 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->OnAppListIsActive(false);
+  }
 }
 
 void AppListPresenterDelegate::UpdateBounds() {