Refactor RegisterViewportLayers to use a struct instead of 6 values

third_party/WebKit/Source/platform/testing/WebLayerTreeViewImplForTesting.h

 // 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.
 
 #ifndef WebLayerTreeViewImplForTesting_h
 #define WebLayerTreeViewImplForTesting_h
 
 #include "cc/test/test_task_graph_runner.h"
 #include "cc/trees/layer_tree_host_client.h"
 #include "cc/trees/layer_tree_host_single_thread_client.h"
@@ skipping 40 matching lines @@
   void SetPageScaleFactorAndLimits(float page_scale_factor,
                                    float minimum,
                                    float maximum) override;
   void StartPageScaleAnimation(const blink::WebPoint& destination,
                                bool use_anchor,
                                float new_page_scale,
                                double duration_sec) override;
   void SetNeedsBeginFrame() override;
   void DidStopFlinging() override;
   void SetDeferCommits(bool) override;
+  // TODO(pdr): Refactor to use a struct like LayerTreeHost::ViewportLayers.
   void RegisterViewportLayers(
       const blink::WebLayer* overscroll_elasticity_layer,
       const blink::WebLayer* page_scale_layer_layer,
       const blink::WebLayer* inner_viewport_container_layer,
       const blink::WebLayer* outer_viewport_container_layer,
       const blink::WebLayer* inner_viewport_scroll_layer,
       const blink::WebLayer* outer_viewport_scroll_layer) override;
   void ClearViewportLayers() override;
   void RegisterSelection(const blink::WebSelection&) override;
   void ClearSelection() override;
@@ skipping 35 matching lines @@
 
  private:
   cc::TestTaskGraphRunner task_graph_runner_;
   std::unique_ptr<cc::AnimationHost> animation_host_;
   std::unique_ptr<cc::LayerTreeHost> layer_tree_host_;
 };
 
 }  // namespace blink
 
 #endif  // WebLayerTreeViewImplForTesting_h