cc: Move SyncedScrollOffset to scroll tree

cc/layers/picture_layer_impl.cc

Index: cc/layers/picture_layer_impl.cc
diff --git a/cc/layers/picture_layer_impl.cc b/cc/layers/picture_layer_impl.cc
index 429a2be14a24b5042353ee5e66f70e7f06cfdf37..da4c67c93f8dac524630a7a663e15cba9911c173 100644
--- a/cc/layers/picture_layer_impl.cc
+++ b/cc/layers/picture_layer_impl.cc
@@ -59,12 +59,10 @@ const int kTileMinimalAlignment = 4;
 
 namespace cc {
 
-PictureLayerImpl::PictureLayerImpl(
-    LayerTreeImpl* tree_impl,
-    int id,
-    bool is_mask,
-    scoped_refptr<SyncedScrollOffset> scroll_offset)
-    : LayerImpl(tree_impl, id, scroll_offset),
+PictureLayerImpl::PictureLayerImpl(LayerTreeImpl* tree_impl,
+                                   int id,
+                                   bool is_mask)
+    : LayerImpl(tree_impl, id),
       twin_layer_(nullptr),
       tilings_(CreatePictureLayerTilingSet()),
       ideal_page_scale_(0.f),
@@ -95,8 +93,7 @@ const char* PictureLayerImpl::LayerTypeAsString() const {
 
 scoped_ptr<LayerImpl> PictureLayerImpl::CreateLayerImpl(
     LayerTreeImpl* tree_impl) {
-  return PictureLayerImpl::Create(tree_impl, id(), is_mask_,
-                                  synced_scroll_offset());
+  return PictureLayerImpl::Create(tree_impl, id(), is_mask_);
 }
 
 void PictureLayerImpl::PushPropertiesTo(LayerImpl* base_layer) {