Update scroll layer positions in WebLayerImpl

webkit/renderer/compositor_bindings/web_layer_impl.cc

 // Copyright 2011 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 "webkit/renderer/compositor_bindings/web_layer_impl.h"
 
 #include "base/bind.h"
 #include "base/strings/string_util.h"
 #include "cc/animation/animation.h"
 #include "cc/base/region.h"
@@ skipping 209 matching lines @@
 }
 
 bool WebLayerImpl::hasActiveAnimation() { return layer_->HasActiveAnimation(); }
 
 void WebLayerImpl::setForceRenderSurface(bool force_render_surface) {
   layer_->SetForceRenderSurface(force_render_surface);
 }
 
 void WebLayerImpl::setScrollPosition(WebKit::WebPoint position) {
   layer_->SetScrollOffset(gfx::Point(position).OffsetFromOrigin());
+  // TODO(enne): Blink currently always updates scroll offset and layer position
+  // in tandem for frames in RenderLayerCompositor::frameViewDidScroll.
+  // So that this can be removed in Blink, temporarily do that work here.
+  // See: http://crbug.com/256381
+  layer_->SetPosition(gfx::PointAtOffsetFromOrigin(-layer_->scroll_offset()));
 }
 
 WebKit::WebPoint WebLayerImpl::scrollPosition() const {
   return gfx::PointAtOffsetFromOrigin(layer_->scroll_offset());
 }
 
 void WebLayerImpl::setMaxScrollPosition(WebSize max_scroll_position) {
   layer_->SetMaxScrollOffset(max_scroll_position);
 }
 
@@ skipping 114 matching lines @@
   layer_->set_did_scroll_callback(
       base::Bind(&WebKit::WebLayerScrollClient::didScroll,
                  base::Unretained(scroll_client)));
 }
 
 bool WebLayerImpl::isOrphan() const { return !layer_->layer_tree_host(); }
 
 Layer* WebLayerImpl::layer() const { return layer_.get(); }
 
 }  // namespace webkit