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

cc/layers/layer_scroll_client.h

Index: cc/layers/layer_scroll_client.h
diff --git a/cc/layers/layer_scroll_client.h b/cc/layers/layer_scroll_client.h
new file mode 100644
index 0000000000000000000000000000000000000000..056cf1aa3967637c6f229b3c3ccaae6da81abc6d
--- /dev/null
+++ b/cc/layers/layer_scroll_client.h
@@ -0,0 +1,20 @@
+// Copyright 2013 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.
+
+#ifndef CC_LAYERS_LAYER_SCROLL_CLIENT_H_
+#define CC_LAYERS_LAYER_SCROLL_CLIENT_H_
+
+namespace cc {
+
+class LayerScrollClient {
+ public:
+  virtual void DidScroll() = 0;

[jamesr, 2013/06/28 00:12:45]

i wonder if instead of a client this should just be a base::Closure - could you
try that?  That'd avoid needing an extra header/etc

+
+ protected:
+  virtual ~LayerScrollClient() {}
+};
+
+}  // namespace cc
+
+#endif  // CC_LAYERS_LAYER_SCROLL_CLIENT_H_