Remove unused ash::SHELF_ALIGNMENT_TOP

ash/wm/panels/attached_panel_window_targeter.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ash/wm/panels/attached_panel_window_targeter.h"
 
 #include "ash/shelf/shelf.h"
 #include "ash/shell.h"
 #include "ash/wm/panels/panel_layout_manager.h"
 
@@ skipping 43 matching lines @@
   switch (panel_layout_manager_->shelf()->alignment()) {
     case SHELF_ALIGNMENT_BOTTOM:
       touch = gfx::Insets(touch.top(), touch.left(), 0, touch.right());
       break;
     case SHELF_ALIGNMENT_LEFT:
       touch = gfx::Insets(touch.top(), 0, touch.bottom(), touch.right());
       break;
     case SHELF_ALIGNMENT_RIGHT:
       touch = gfx::Insets(touch.top(), touch.left(), touch.bottom(), 0);
       break;
-    case SHELF_ALIGNMENT_TOP:
-      touch = gfx::Insets(0, touch.left(), touch.bottom(), touch.right());
-      break;
-    default:
-      NOTREACHED();
-      return;
   }
 
   set_touch_extend(touch);
 }
 
 }  // namespace ash