cc: Move SyncedScrollOffset to scroll tree

cc/layers/picture_layer.cc

 // Copyright 2012 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.
 
 #include "cc/layers/picture_layer.h"
 
 #include "base/auto_reset.h"
 #include "base/trace_event/trace_event.h"
 #include "cc/layers/content_layer_client.h"
 #include "cc/layers/picture_layer_impl.h"
@@ skipping 28 matching lines @@
                            scoped_ptr<DisplayListRecordingSource> source)
     : PictureLayer(settings, client) {
   recording_source_ = std::move(source);
 }
 
 PictureLayer::~PictureLayer() {
 }
 
 scoped_ptr<LayerImpl> PictureLayer::CreateLayerImpl(LayerTreeImpl* tree_impl) {
   return PictureLayerImpl::Create(tree_impl, id(), is_mask_,
-                                  new LayerImpl::SyncedScrollOffset);
+                                  new SyncedScrollOffset);
 }
 
 void PictureLayer::PushPropertiesTo(LayerImpl* base_layer) {
   Layer::PushPropertiesTo(base_layer);
   TRACE_EVENT0("cc", "PictureLayer::PushPropertiesTo");
   PictureLayerImpl* layer_impl = static_cast<PictureLayerImpl*>(base_layer);
   // TODO(danakj): Make is_mask_ a constructor parameter for PictureLayer.
   DCHECK_EQ(layer_impl->is_mask(), is_mask_);
   DropRecordingSourceContentIfInvalid();
 
@@ skipping 195 matching lines @@
   if (update_source_frame_number_ != source_frame_number &&
       recording_source_bounds != layer_bounds) {
     // Update may not get called for the layer (if it's not in the viewport
     // for example), even though it has resized making the recording source no
     // longer valid. In this case just destroy the recording source.
     recording_source_->SetEmptyBounds();
   }
 }
 
 }  // namespace cc