Adding momentum/overscroll to views:: ScrollViews

ui/compositor/layer.cc

Index: ui/compositor/layer.cc
diff --git a/ui/compositor/layer.cc b/ui/compositor/layer.cc
index 83409bb748fc9d82976b43678174cd4612f488be..bbe0418f8c2b39f3f9da89e5e8a46e268144f70d 100644
--- a/ui/compositor/layer.cc
+++ b/ui/compositor/layer.cc
@@ -528,6 +528,36 @@ void Layer::SwitchCCLayerForTest() {
   content_layer_ = new_layer;
 }
 
+gfx::ScrollOffset Layer::CurrentScrollOffset() const {
+  return cc_layer_->scroll_offset();
+}
+
+void Layer::SetScrollOffset(const gfx::ScrollOffset& offset) {
+#if 0
+  if (IsDrawn())
+    ScheduleDraw();
+  cc_layer_->SetScrollOffsetFromImplSide(offset, nullptr);
+#else
+  bool scrolled_on_impl_side =
+      GetCompositor() &&
+      GetCompositor()->ScrollLayerTo(cc_layer_->id(), offset);
+
+  if (!scrolled_on_impl_side)
+    cc_layer_->SetScrollOffset(offset);
+#endif
+}
+
+void Layer::SetScrollable(Layer* parent_clip_layer,
+                          bool can_overscroll,
+                          const base::Closure& on_scroll) {
+  cc_layer_->SetScrollParent(parent_clip_layer->cc_layer_);
+  cc_layer_->SetIsContainerForFixedPositionLayers(true);
+  cc_layer_->SetScrollClipAndCanOverscroll(parent_clip_layer->cc_layer_->id(),
+                                           can_overscroll);
+  cc_layer_->set_did_scroll_callback(on_scroll);
+  cc_layer_->SetUserScrollable(true, true);
+}
+
 void Layer::SetTextureMailbox(
     const cc::TextureMailbox& mailbox,
     std::unique_ptr<cc::SingleReleaseCallback> release_callback,