While dragging a window, show a semi-transparent aura window instead of the standard gray phantom wi

ash/wm/window_resizer.cc

 // Copyright (c) 2012 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/window_resizer.h"
 
 #include "ash/screen_ash.h"
 #include "ash/shell.h"
 #include "ui/aura/client/aura_constants.h"
 #include "ui/aura/root_window.h"
@@ skipping 95 matching lines @@
       size_change_direction(0),
       is_resizable(false) {
 }
 
 WindowResizer::Details::Details(aura::Window* window,
                                 const gfx::Point& location,
                                 int window_component)
   : window(window),
     initial_bounds(window->bounds()),
     initial_location_in_parent(location),
+    initial_opacity(window->layer()->opacity()),
     window_component(window_component),
     bounds_change(GetBoundsChangeForWindowComponent(window_component)),
     position_change_direction(
         GetPositionChangeDirectionForWindowComponent(window_component)),
     size_change_direction(
         GetSizeChangeDirectionForWindowComponent(window_component)),
     is_resizable(bounds_change != kBoundsChangeDirection_None) {
 }
 
 WindowResizer::Details::~Details() {
@@ skipping 206 matching lines @@
         gfx::Screen::GetDisplayNearestWindow(details.window).bounds().height();
     if (height > max_height) {
       height = max_height;
       *delta_y = -y_multiplier * (details.initial_bounds.height() - max_height);
     }
   }
   return height;
 }
 
 }  // namespace aura