Add second copy request after screen rotation to flatten the layers in animation.

ash/rotator/test/screen_rotation_animator_test_api.cc

 // Copyright 2017 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 "ash/rotator/test/screen_rotation_animator_test_api.h"
 
 #include "ash/rotator/screen_rotation_animator.h"
 #include "ui/compositor/layer.h"
 #include "ui/compositor/layer_tree_owner.h"
 
@@ skipping 10 matching lines @@
   animator_->set_disable_animation_timers_for_test(true);
 }
 
 std::vector<ui::LayerAnimator*>
 ScreenRotationAnimatorTestApi::GetLayerAnimators() {
   std::vector<ui::LayerAnimator*> animators;
   if (animator_->old_layer_tree_owner_) {
     animators.insert(animators.end(),
                      animator_->old_layer_tree_owner_->root()->GetAnimator());
   }
+  if (animator_->new_layer_tree_owner_) {
+    animators.insert(animators.end(),
+                     animator_->new_layer_tree_owner_->root()->GetAnimator());
+  }
   return animators;
 }
 
 }  // namespace test
 }  // namespace ash