Remove GraphicsLayer::didScroll and directly call ScrollableArea::didScroll

cc/blink/web_layer_impl.cc

 // Copyright 2014 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/blink/web_layer_impl.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <utility>
@@ skipping 398 matching lines @@
   return ToWebLayerStickyPositionConstraint(
       layer_->sticky_position_constraint());
 }
 
 void WebLayerImpl::setScrollClient(blink::WebLayerScrollClient* scroll_client) {
   if (scroll_client) {
     layer_->set_did_scroll_callback(
         base::Bind(&blink::WebLayerScrollClient::didScroll,
                    base::Unretained(scroll_client)));
   } else {
-    layer_->set_did_scroll_callback(base::Closure());
+    layer_->set_did_scroll_callback(
+        base::Callback<void(const gfx::ScrollOffset&)>());
   }
 }
 
 void WebLayerImpl::setLayerClient(cc::LayerClient* client) {
   layer_->SetLayerClient(client);
 }
 
 const cc::Layer* WebLayerImpl::ccLayer() const {
   return layer_.get();
 }
@@ skipping 46 matching lines @@
 
 void WebLayerImpl::setPreferredRasterBounds(const WebSize& bounds) {
   layer_->SetPreferredRasterBounds(bounds);
 }
 
 void WebLayerImpl::clearPreferredRasterBounds() {
   layer_->ClearPreferredRasterBounds();
 }
 
 }  // namespace cc_blink