Reland r206537 - cc: Don't return mailboxes if the TextureLayer is removed from the tree.

cc/layers/texture_layer_impl.cc

 // Copyright 2011 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 "cc/layers/texture_layer_impl.h"
 
 #include "base/strings/stringprintf.h"
 #include "cc/layers/quad_sink.h"
 #include "cc/output/renderer.h"
 #include "cc/quads/texture_draw_quad.h"
@@ skipping 16 matching lines @@
   vertex_opacity_[0] = 1.0f;
   vertex_opacity_[1] = 1.0f;
   vertex_opacity_[2] = 1.0f;
   vertex_opacity_[3] = 1.0f;
 }
 
 TextureLayerImpl::~TextureLayerImpl() { FreeTextureMailbox(); }
 
 void TextureLayerImpl::SetTextureMailbox(const TextureMailbox& mailbox) {
   DCHECK(uses_mailbox_);
-  if (own_mailbox_)
-    DCHECK(!mailbox.IsValid() || !mailbox.Equals(texture_mailbox_));
   FreeTextureMailbox();
   texture_mailbox_ = mailbox;
   own_mailbox_ = true;
 }
 
 scoped_ptr<LayerImpl> TextureLayerImpl::CreateLayerImpl(
     LayerTreeImpl* tree_impl) {
   return TextureLayerImpl::Create(tree_impl, id(), uses_mailbox_).
       PassAs<LayerImpl>();
 }
@@ skipping 114 matching lines @@
   } else if (external_texture_resource_) {
     DCHECK(!own_mailbox_);
     ResourceProvider* resource_provider =
         layer_tree_impl()->resource_provider();
     resource_provider->DeleteResource(external_texture_resource_);
     external_texture_resource_ = 0;
   }
 }
 
 }  // namespace cc