Revert of Remove indirection: setup scrollbar scroll layers in the scrollbar constructor

cc/blink/web_scrollbar_layer_impl.h

Index: cc/blink/web_scrollbar_layer_impl.h
diff --git a/cc/blink/web_scrollbar_layer_impl.h b/cc/blink/web_scrollbar_layer_impl.h
index 657c90a70e081bdcd3ceaa18bf48f9b3e3c28dea..ad203e9a9563e115e5779e865f57aa07fb3bc700 100644
--- a/cc/blink/web_scrollbar_layer_impl.h
+++ b/cc/blink/web_scrollbar_layer_impl.h
@@ -26,19 +26,22 @@
   CC_BLINK_EXPORT WebScrollbarLayerImpl(
       std::unique_ptr<blink::WebScrollbar> scrollbar,
       blink::WebScrollbarThemePainter painter,
+      std::unique_ptr<blink::WebScrollbarThemeGeometry> geometry);
+  CC_BLINK_EXPORT WebScrollbarLayerImpl(
+      std::unique_ptr<blink::WebScrollbar> scrollbar,
+      blink::WebScrollbarThemePainter painter,
       std::unique_ptr<blink::WebScrollbarThemeGeometry> geometry,
-      bool is_overlay,
-      blink::WebLayer* scroll_layer);
+      bool temp);
   CC_BLINK_EXPORT WebScrollbarLayerImpl(
       blink::WebScrollbar::Orientation orientation,
       int thumb_thickness,
       int track_start,
-      bool is_left_side_vertical_scrollbar,
-      blink::WebLayer* scroll_layer);
+      bool is_left_side_vertical_scrollbar);
   ~WebScrollbarLayerImpl() override;
 
   // blink::WebScrollbarLayer implementation.
   blink::WebLayer* layer() override;
+  void setScrollLayer(blink::WebLayer* layer) override;
 
  private:
   std::unique_ptr<WebLayerImpl> layer_;