Prevent recreation of UI resource holder when created with resource ID

cc/layers/ui_resource_layer_unittest.cc

 // Copyright 2013 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/ui_resource_layer.h"
 
 #include "cc/resources/prioritized_resource_manager.h"
 #include "cc/resources/resource_provider.h"
 #include "cc/resources/resource_update_queue.h"
 #include "cc/resources/scoped_ui_resource.h"
@@ skipping 84 matching lines @@
 
   EXPECT_FALSE(test_layer->DrawsContent());
 
   bool is_opaque = false;
   scoped_ptr<ScopedUIResource> resource = ScopedUIResource::Create(
       layer_tree_host_.get(), UIResourceBitmap(gfx::Size(10, 10), is_opaque));
   test_layer->SetUIResourceId(resource->id());
   test_layer->Update(&queue, &occlusion_tracker);
 
   EXPECT_TRUE(test_layer->DrawsContent());
+
+  // ID is preserved even when you set ID first and attach it to the tree.
+  scoped_refptr<UIResourceLayer> new_test_layer = UIResourceLayer::Create();
+  scoped_ptr<ScopedUIResource> new_resource = ScopedUIResource::Create(
+      layer_tree_host_.get(), UIResourceBitmap(gfx::Size(5, 5), is_opaque));
+  new_test_layer->SetUIResourceId(new_resource->id());
+  test_layer->AddChild(new_test_layer);
+  EXPECT_EQ(new_resource->id(), new_test_layer->GetUIResourceId());
 }
 
 }  // namespace
 }  // namespace cc