chromeos: Rename ash::WmShelf to Shelf

ash/system/lock_screen_action/lock_screen_action_tray.cc

Index: ash/system/lock_screen_action/lock_screen_action_tray.cc
diff --git a/ash/system/lock_screen_action/lock_screen_action_tray.cc b/ash/system/lock_screen_action/lock_screen_action_tray.cc
index b113945e256f85c903654eda06c29099518683b4..bc475b6533dbf8cdcadda1fd695da866e561ef7e 100644
--- a/ash/system/lock_screen_action/lock_screen_action_tray.cc
+++ b/ash/system/lock_screen_action/lock_screen_action_tray.cc
@@ -55,8 +55,8 @@ class LockScreenActionTray::NewNoteActionView : public views::View {
   DISALLOW_COPY_AND_ASSIGN(NewNoteActionView);
 };
 
-LockScreenActionTray::LockScreenActionTray(WmShelf* wm_shelf)
-    : TrayBackgroundView(wm_shelf),
+LockScreenActionTray::LockScreenActionTray(Shelf* shelf)
+    : TrayBackgroundView(shelf),
       session_observer_(this),
       tray_action_observer_(this) {
   SetInkDropMode(InkDropMode::ON);