cc: Clean up root_layer code in LTI

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 <stddef.h>
 
 #include "base/location.h"
 #include "base/memory/ptr_util.h"
 #include "base/single_thread_task_runner.h"
 #include "base/threading/thread_task_runner_handle.h"
@@ skipping 1176 matching lines @@
           CopyOutputRequest::CreateBitmapRequest(base::Bind(
               &LayerTreeHostCopyRequestTestMultipleDrawsHiddenCopyRequest::
                   CopyOutputCallback,
               base::Unretained(this))));
     }
   }
 
   DrawResult PrepareToDrawOnThread(LayerTreeHostImpl* host_impl,
                                    LayerTreeHostImpl::FrameData* frame_data,
                                    DrawResult draw_result) override {
-    LayerImpl* root = host_impl->active_tree()->root_layer();
+    LayerImpl* root = host_impl->active_tree()->root_layer_for_testing();
     LayerImpl* child = host_impl->active_tree()->LayerById(child_->id());
 
     bool saw_root = false;
     bool saw_child = false;
     for (LayerIterator it =
              LayerIterator::Begin(frame_data->render_surface_layer_list);
          it != LayerIterator::End(frame_data->render_surface_layer_list);
          ++it) {
       if (it.represents_itself()) {
         if (*it == root)
@@ skipping 59 matching lines @@
   int num_draws_;
   bool copy_happened_;
   bool draw_happened_;
 };
 
 SINGLE_AND_MULTI_THREAD_DIRECT_RENDERER_TEST_F(
     LayerTreeHostCopyRequestTestMultipleDrawsHiddenCopyRequest);
 
 }  // namespace
 }  // namespace cc