Revert of Draggable peeking/fullscreen launcher with transparent background.

ash/shelf/app_list_button.cc

Index: ash/shelf/app_list_button.cc
diff --git a/ash/shelf/app_list_button.cc b/ash/shelf/app_list_button.cc
index efecc294aa093c4b389fae44cf1998ee35148f06..584d9d842d223fcaf91911116abcb9d32d96a0be 100644
--- a/ash/shelf/app_list_button.cc
+++ b/ash/shelf/app_list_button.cc
@@ -44,7 +44,7 @@
   DCHECK(listener_);
   DCHECK(shelf_view_);
   DCHECK(shelf_);
-  Shell::Get()->AddShellObserver(this);
+
   SetInkDropMode(InkDropMode::ON_NO_GESTURE_HANDLER);
   set_ink_drop_base_color(kShelfInkDropBaseColor);
   set_ink_drop_visible_opacity(kShelfInkDropVisibleOpacity);
@@ -55,9 +55,7 @@
   set_notify_action(CustomButton::NOTIFY_ON_PRESS);
 }
 
-AppListButton::~AppListButton() {
-  Shell::Get()->RemoveShellObserver(this);
-}
+AppListButton::~AppListButton() {}
 
 void AppListButton::OnAppListShown() {
   AnimateInkDrop(views::InkDropState::ACTIVATED, nullptr);
@@ -241,15 +239,4 @@
   }
 }
 
-void AppListButton::OnAppListVisibilityChanged(bool shown,
-                                               aura::Window* root_window) {
-  if (shelf_ != Shelf::ForWindow(root_window))
-    return;
-
-  if (shown)
-    OnAppListShown();
-  else
-    OnAppListDismissed();
-}
-
 }  // namespace ash