Refactor RegisterViewportLayers to use a struct instead of 6 values

cc/trees/layer_tree_host.h

 // Copyright 2011 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 CC_TREES_LAYER_TREE_HOST_H_
 #define CC_TREES_LAYER_TREE_HOST_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 223 matching lines @@
   void SetNextCommitWaitsForActivation();
 
   // The LayerTreeHost tracks whether the content is suitable for Gpu raster.
   // Calling this will reset it back to not suitable state.
   void ResetGpuRasterizationTracking();
 
   void SetRootLayer(scoped_refptr<Layer> root_layer);
   Layer* root_layer() { return root_layer_.get(); }
   const Layer* root_layer() const { return root_layer_.get(); }
 
-  void RegisterViewportLayers(
-      scoped_refptr<Layer> overscroll_elasticity_layer,
-      scoped_refptr<Layer> page_scale_layer,
-      scoped_refptr<Layer> inner_viewport_container_layer,
-      scoped_refptr<Layer> outer_viewport_container_layer,
-      scoped_refptr<Layer> inner_viewport_scroll_layer,
-      scoped_refptr<Layer> outer_viewport_scroll_layer);
-
+  struct CC_EXPORT ViewportLayers {
+    ViewportLayers();
+    ~ViewportLayers();
+    scoped_refptr<Layer> overscroll_elasticity;
+    scoped_refptr<Layer> page_scale;
+    scoped_refptr<Layer> inner_viewport_container;
+    scoped_refptr<Layer> outer_viewport_container;
+    scoped_refptr<Layer> inner_viewport_scroll;
+    scoped_refptr<Layer> outer_viewport_scroll;
+  };
+  void RegisterViewportLayers(const ViewportLayers& viewport_layers);
   Layer* overscroll_elasticity_layer() const {
-    return overscroll_elasticity_layer_.get();
+    return viewport_layers_.overscroll_elasticity.get();
   }
-  Layer* page_scale_layer() const { return page_scale_layer_.get(); }
+  Layer* page_scale_layer() const { return viewport_layers_.page_scale.get(); }
   Layer* inner_viewport_container_layer() const {
-    return inner_viewport_container_layer_.get();
+    return viewport_layers_.inner_viewport_container.get();
   }
   Layer* outer_viewport_container_layer() const {
-    return outer_viewport_container_layer_.get();
+    return viewport_layers_.outer_viewport_container.get();
   }
   Layer* inner_viewport_scroll_layer() const {
-    return inner_viewport_scroll_layer_.get();
+    return viewport_layers_.inner_viewport_scroll.get();
   }
   Layer* outer_viewport_scroll_layer() const {
-    return outer_viewport_scroll_layer_.get();
+    return viewport_layers_.outer_viewport_scroll.get();
   }
 
   void RegisterSelection(const LayerSelection& selection);
   const LayerSelection& selection() const { return selection_; }
 
   void SetHaveScrollEventHandlers(bool have_event_handlers);
   bool have_scroll_event_handlers() const {
     return have_scroll_event_handlers_;
   }
 
@@ skipping 287 matching lines @@
   // destroyed midway which causes a crash. crbug.com/654672
   bool inside_main_frame_ = false;
 
   TaskGraphRunner* task_graph_runner_;
 
   SurfaceSequenceGenerator surface_sequence_generator_;
   uint32_t num_consecutive_frames_suitable_for_gpu_ = 0;
 
   scoped_refptr<Layer> root_layer_;
 
-  scoped_refptr<Layer> overscroll_elasticity_layer_;
-  scoped_refptr<Layer> page_scale_layer_;
-  scoped_refptr<Layer> inner_viewport_container_layer_;
-  scoped_refptr<Layer> outer_viewport_container_layer_;
-  scoped_refptr<Layer> inner_viewport_scroll_layer_;
-  scoped_refptr<Layer> outer_viewport_scroll_layer_;
+  ViewportLayers viewport_layers_;
 
   float top_controls_height_ = 0.f;
   float top_controls_shown_ratio_ = 0.f;
   bool browser_controls_shrink_blink_size_ = false;
 
   float bottom_controls_height_ = 0.f;
 
   float device_scale_factor_ = 1.f;
   float painted_device_scale_factor_ = 1.f;
   float page_scale_factor_ = 1.f;
@@ skipping 46 matching lines @@
 
   std::vector<std::pair<sk_sp<const SkImage>, base::Callback<void(bool)>>>
       queued_image_decodes_;
 
   DISALLOW_COPY_AND_ASSIGN(LayerTreeHost);
 };
 
 }  // namespace cc
 
 #endif  // CC_TREES_LAYER_TREE_HOST_H_