cc: Remove use of PassAs() and constructor-casting with scoped_ptr.

cc/trees/layer_tree_host_unittest_copyrequest.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/output/copy_output_request.h"
 #include "cc/output/copy_output_result.h"
 #include "cc/test/fake_content_layer.h"
 #include "cc/test/fake_content_layer_client.h"
 #include "cc/test/fake_output_surface.h"
 #include "cc/test/layer_tree_test.h"
@@ skipping 574 matching lines @@
                             CopyOutputCallback,
                        base::Unretained(this))));
         break;
       case 4:
       // With SingleThreadProxy it takes two commits to finally swap after a
       // context loss.
       case 5:
         // Now destroy the CopyOutputResult, releasing the texture inside back
         // to the compositor.
         EXPECT_TRUE(result_);
-        result_.reset();
+        result_ = nullptr;
 
         // Check that it is released.
         ImplThreadTaskRunner()->PostTask(
             FROM_HERE,
             base::Bind(&LayerTreeHostCopyRequestTestLostOutputSurface::
                             CheckNumTextures,
                        base::Unretained(this),
                        num_textures_after_loss_ - 1));
         break;
     }
@@ skipping 359 matching lines @@
   FakeContentLayerClient client_;
   scoped_refptr<FakeContentLayer> root_;
   scoped_refptr<FakeContentLayer> copy_layer_;
 };
 
 SINGLE_AND_MULTI_THREAD_DIRECT_RENDERER_TEST_F(
     LayerTreeHostCopyRequestTestShutdownBeforeCopy);
 
 }  // namespace
 }  // namespace cc