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

ui/aura/window.cc

Index: ui/aura/window.cc
diff --git a/ui/aura/window.cc b/ui/aura/window.cc
index 84251126124a73826eba0e2902705ad7cd20139a..f43f0e0f3de19bd53bf84c386b400c2ea8342d4c 100644
--- a/ui/aura/window.cc
+++ b/ui/aura/window.cc
@@ -144,14 +144,22 @@ ui::Layer* Window::RecreateLayer() {
     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.