[Refactor] Kill some dead code because it is no longer possible to drag maximized windows

ash/wm/drag_details.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/drag_details.h"
 
 #include "ash/wm/window_resizer.h"
 #include "ui/aura/window.h"
 #include "ui/base/hit_test.h"
 
@@ skipping 41 matching lines @@
       bounds_change(
           WindowResizer::GetBoundsChangeForWindowComponent(window_component)),
       position_change_direction(
           WindowResizer::GetPositionChangeDirectionForWindowComponent(
               window_component)),
       size_change_direction(
           GetSizeChangeDirectionForWindowComponent(window_component)),
       is_resizable(bounds_change != WindowResizer::kBoundsChangeDirection_None),
       source(source),
       should_attach_to_shelf(window->type() == ui::wm::WINDOW_TYPE_PANEL &&
-                             wm::GetWindowState(window)->panel_attached()),
-      window_resizer(NULL) {
+                             wm::GetWindowState(window)->panel_attached()) {
   wm::WindowState* window_state = wm::GetWindowState(window);
   if (window_state->IsNormalShowState() &&
       window_state->HasRestoreBounds() &&
       window_component == HTCAPTION)
     restore_bounds = window_state->GetRestoreBoundsInScreen();
 }
 
 DragDetails::~DragDetails() {
 }
 
 }  // namespace ash