cc: Impl thread scroll on ScrollNode instead of LayerImpl

cc/layers/layer_impl.h

Index: cc/layers/layer_impl.h
diff --git a/cc/layers/layer_impl.h b/cc/layers/layer_impl.h
index ef7db537f45d527d953de2fe4c9e9b3723bc5809..a8de2bb5c62fda807e48889a7d24706bf48a58e3 100644
--- a/cc/layers/layer_impl.h
+++ b/cc/layers/layer_impl.h
@@ -441,15 +441,11 @@ class CC_EXPORT LayerImpl {
   LayerImpl* scroll_clip_layer() const;
   bool scrollable() const;
 
-  void set_user_scrollable_horizontal(bool scrollable) {
-    user_scrollable_horizontal_ = scrollable;
-  }
+  void set_user_scrollable_horizontal(bool scrollable);
   bool user_scrollable_horizontal() const {
     return user_scrollable_horizontal_;
   }
-  void set_user_scrollable_vertical(bool scrollable) {
-    user_scrollable_vertical_ = scrollable;
-  }
+  void set_user_scrollable_vertical(bool scrollable);
   bool user_scrollable_vertical() const { return user_scrollable_vertical_; }
 
   bool user_scrollable(ScrollbarOrientation orientation) const;