cc: Create a LayerScrollClient interface and an adapter class in compositor_bindings.

webkit/renderer/compositor_bindings/web_layer_impl.cc

Index: webkit/renderer/compositor_bindings/web_layer_impl.cc
diff --git a/webkit/renderer/compositor_bindings/web_layer_impl.cc b/webkit/renderer/compositor_bindings/web_layer_impl.cc
index d46b9e12980a63aa849f68d19aac84e1bfca4109..16dc1e0c121044f3d6127f17bf1aa4cfe760fc55 100644
--- a/webkit/renderer/compositor_bindings/web_layer_impl.cc
+++ b/webkit/renderer/compositor_bindings/web_layer_impl.cc
@@ -18,6 +18,7 @@
 #include "webkit/renderer/compositor_bindings/web_animation_impl.h"
 #include "webkit/renderer/compositor_bindings/web_filter_operations_impl.h"
 #include "webkit/renderer/compositor_bindings/web_to_cc_animation_delegate_adapter.h"
+#include "webkit/renderer/compositor_bindings/web_to_cc_layer_scroll_client_adapter.h"
 
 using cc::Animation;
 using cc::Layer;
@@ -358,7 +359,9 @@ WebKit::WebLayerPositionConstraint WebLayerImpl::positionConstraint() const {
 
 void WebLayerImpl::setScrollClient(
     WebKit::WebLayerScrollClient* scroll_client) {
-  layer_->set_layer_scroll_client(scroll_client);
+  layer_scroll_client_adapter_.reset(
+      new WebToCCLayerScrollClientAdapter(scroll_client));
+  layer_->set_layer_scroll_client(layer_scroll_client_adapter_.get());

[danakj, 2013/06/28 02:57:48]

To do this with base::Callback, you'd add a method here

static void PassAlongDidScroll(WebLayerScrollClient* scroll_client) {
  scroll_client->didScroll();
}

Then you'd give to cc something like

layer->set_did_scroll_callback(base::Bind(&PassAlongDidScroll,
base::Unretained(scroll_client)));

Then cc receives and stores a base::Closure that it calls Run() on instead of
calling client->DidScroll().

[danakj, 2013/06/28 02:59:02]

Actually, you shouldn't need the PassAlong method. You should be able to just
give cc a base::Bind(WebLayerScrollClient::didScroll,
base::Unretained(scroll_client)) I believe.

[tfarina, 2013/06/28 04:07:03]

Done.

 }
 
 bool WebLayerImpl::isOrphan() const { return !layer_->layer_tree_host(); }