Convert scroll offsets to use SyncedProperty.

cc/layers/picture_layer_impl.h

Index: cc/layers/picture_layer_impl.h
diff --git a/cc/layers/picture_layer_impl.h b/cc/layers/picture_layer_impl.h
index 4b4816ad03906227a9f696f920bcfbe777ec51bb..fa406839fc3e304b25969972de5b187f7cbed1ed 100644
--- a/cc/layers/picture_layer_impl.h
+++ b/cc/layers/picture_layer_impl.h
@@ -38,10 +38,13 @@ class CC_EXPORT PictureLayerImpl
     PictureLayerImpl* pending;
   };
 
-  static scoped_ptr<PictureLayerImpl> Create(LayerTreeImpl* tree_impl,
-                                             int id,
-                                             bool is_mask) {
-    return make_scoped_ptr(new PictureLayerImpl(tree_impl, id, is_mask));
+  static scoped_ptr<PictureLayerImpl> Create(
+      LayerTreeImpl* tree_impl,
+      int id,
+      bool is_mask,
+      scoped_refptr<SyncedScrollOffset> scroll_offset) {
+    return make_scoped_ptr(
+        new PictureLayerImpl(tree_impl, id, is_mask, scroll_offset));
   }
   ~PictureLayerImpl() override;
 
@@ -105,7 +108,10 @@ class CC_EXPORT PictureLayerImpl
   friend class LayerRasterTileIterator;
   using TileRequirementCheck = bool (PictureLayerTiling::*)(const Tile*) const;
 
-  PictureLayerImpl(LayerTreeImpl* tree_impl, int id, bool is_mask);
+  PictureLayerImpl(LayerTreeImpl* tree_impl,
+                   int id,
+                   bool is_mask,
+                   scoped_refptr<SyncedScrollOffset> scroll_offset);
   PictureLayerTiling* AddTiling(float contents_scale);
   void RemoveAllTilings();
   void AddTilingsForRasterScale();