Refactor RegisterViewportLayers to use a struct instead of 6 values

cc/layers/layer_position_constraint_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/layer_position_constraint.h"
 
 #include <vector>
 
 #include "cc/animation/animation_host.h"
 #include "cc/layers/layer.h"
@@ skipping 117 matching lines @@
 
     grand_child_->AddChild(great_grand_child_);
     child_->AddChild(grand_child_);
     child_transform_layer_->AddChild(child_);
     outer_viewport_container_layer_->AddChild(child_transform_layer_);
     scroll_layer_->AddChild(outer_viewport_container_layer_);
     inner_viewport_container_layer_->AddChild(scroll_layer_);
     root_->AddChild(inner_viewport_container_layer_);
 
     layer_tree_host_->SetRootLayer(root_);
-    layer_tree_host_->RegisterViewportLayers(
-        nullptr, root_, inner_viewport_container_layer_,
-        outer_viewport_container_layer_, scroll_layer_, child_);
+    LayerTreeHost::ViewportLayers viewport_layers;
+    viewport_layers.page_scale = root_;
+    viewport_layers.inner_viewport_container = inner_viewport_container_layer_;
+    viewport_layers.outer_viewport_container = outer_viewport_container_layer_;
+    viewport_layers.inner_viewport_scroll = scroll_layer_;
+    viewport_layers.outer_viewport_scroll = child_;
+    layer_tree_host_->RegisterViewportLayers(viewport_layers);
   }
 
   void CommitAndUpdateImplPointers() {
     LayerTreeHostCommon::CalcDrawPropsMainInputsForTesting inputs(
         root_.get(), root_->bounds());
     inputs.inner_viewport_scroll_layer =
         layer_tree_host_->inner_viewport_scroll_layer();
     inputs.outer_viewport_scroll_layer =
         layer_tree_host_->outer_viewport_scroll_layer();
     LayerTreeHostCommon::CalculateDrawPropertiesForTesting(&inputs);
@@ skipping 995 matching lines @@
   expected_fixed_child_transform.Translate(20.0, 20.0);
 
   EXPECT_TRANSFORMATION_MATRIX_EQ(expected_scroll_layer_transform,
                                   scroll_layer_impl_->DrawTransform());
   EXPECT_TRANSFORMATION_MATRIX_EQ(expected_fixed_child_transform,
                                   fixed_child_impl->DrawTransform());
 }
 
 }  // namespace
 }  // namespace cc