Set the original external texture to new layer when it's copied to the old layer.

ui/aura/window.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 "ui/aura/window.h"
 
 #include <algorithm>
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
@@ skipping 126 matching lines @@
   Env::GetInstance()->NotifyWindowInitialized(this);
 }
 
 ui::Layer* Window::RecreateLayer() {
   // Disconnect the old layer, but don't delete it.
   ui::Layer* old_layer = AcquireLayer();
   if (!old_layer)
     return NULL;
 
   old_layer->set_delegate(NULL);
-  if (delegate_ && old_layer->external_texture())
+  scoped_refptr<ui::Texture> old_texture = old_layer->external_texture();
+  if (delegate_ && old_texture)
     old_layer->SetExternalTexture(delegate_->CopyTexture());
+
   layer_ = new ui::Layer(old_layer->type());
   layer_owner_.reset(layer_);
   layer_->SetVisible(old_layer->visible());
   layer_->set_scale_content(old_layer->scale_content());
   layer_->set_delegate(this);
   layer_->SetMasksToBounds(old_layer->GetMasksToBounds());
+  // Move the original texture to the new layer if the old layer has a
+  // texture and we could copy it into the old layer,
+  // crbug.com/175211.
+  if (delegate_ && old_texture)

[sky, 2013/02/12 03:31:54]

This code is also hit when maximizing. Does setting an external texture like
this lead to any problems there?

[oshima, 2013/02/12 04:03:23]

I tested (un)maximizing as well and it looks fine.
I guess this was hard to notice with maxizming as the new layer is fading in?

[sky, 2013/02/12 17:01:24]

When you maximize/restore we change the size immediately after this. Which
should mean the old texture isn't used. I just wanted to make sure your code
didn't cause any artifacats there.

+    layer_->SetExternalTexture(old_texture);
+
   UpdateLayerName(name_);
   layer_->SetFillsBoundsOpaquely(!transparent_);
   // Install new layer as a sibling of the old layer, stacked on top of it.
   if (old_layer->parent()) {
     old_layer->parent()->Add(layer_);
     old_layer->parent()->StackAbove(layer_, old_layer);
   }
   // Migrate all the child layers over to the new layer. Copy the list because
   // the items are removed during iteration.
   std::vector<ui::Layer*> children_copy = old_layer->children();
@@ skipping 864 matching lines @@
   bool contains_mouse = false;
   if (IsVisible()) {
     RootWindow* root_window = GetRootWindow();
     contains_mouse = root_window &&
         ContainsPointInRoot(root_window->GetLastMouseLocationInRoot());
   }
   return contains_mouse;
 }
 
 }  // namespace aura