End-to-end prototype of compositor scrolling with slimming paint v2

cc/blink/web_layer_impl.cc

Index: cc/blink/web_layer_impl.cc
diff --git a/cc/blink/web_layer_impl.cc b/cc/blink/web_layer_impl.cc
index 73e62b3e66fc0f018aa19bf2484402d08a1b69af..345ea3ea64adec1aec1c40c02c376dca598f7d4a 100644
--- a/cc/blink/web_layer_impl.cc
+++ b/cc/blink/web_layer_impl.cc
@@ -416,7 +416,8 @@ void WebLayerImpl::setScrollClient(blink::WebLayerScrollClient* scroll_client) {
         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&)>());
   }
 }