chromeos: Rename ash::WmShelf to Shelf

ash/system/status_area_widget.h

Index: ash/system/status_area_widget.h
diff --git a/ash/system/status_area_widget.h b/ash/system/status_area_widget.h
index f93ff55b9f96c0dcee2bc77d4e3350b315c08867..dbb5feac2230324c70b7b54e9dde57c14459036f 100644
--- a/ash/system/status_area_widget.h
+++ b/ash/system/status_area_widget.h
@@ -22,16 +22,16 @@ class LockScreenActionTray;
 class LogoutButtonTray;
 class OverviewButtonTray;
 class PaletteTray;
+class Shelf;
 class StatusAreaWidgetDelegate;
 class SystemTray;
 class VirtualKeyboardTray;
 class WebNotificationTray;
-class WmShelf;
 
 class ASH_EXPORT StatusAreaWidget : public views::Widget,
                                     public ShelfBackgroundAnimatorObserver {
  public:
-  StatusAreaWidget(aura::Window* status_container, WmShelf* wm_shelf);
+  StatusAreaWidget(aura::Window* status_container, Shelf* shelf);
   ~StatusAreaWidget() override;
 
   // Creates the SystemTray, WebNotificationTray and LogoutButtonTray.
@@ -62,7 +62,7 @@ class ASH_EXPORT StatusAreaWidget : public views::Widget,
 
   ImeMenuTray* ime_menu_tray() { return ime_menu_tray_; }
 
-  WmShelf* wm_shelf() { return wm_shelf_; }
+  Shelf* shelf() { return shelf_; }
 
   LoginStatus login_status() const { return login_status_; }
 
@@ -119,7 +119,7 @@ class ASH_EXPORT StatusAreaWidget : public views::Widget,
   ImeMenuTray* ime_menu_tray_;
   LoginStatus login_status_;
 
-  WmShelf* wm_shelf_;
+  Shelf* shelf_;
 
   DISALLOW_COPY_AND_ASSIGN(StatusAreaWidget);
 };