WIP - compositor worker mega patch.

cc/layers/layer_impl.cc

Index: cc/layers/layer_impl.cc
diff --git a/cc/layers/layer_impl.cc b/cc/layers/layer_impl.cc
index 3837bca46148ae930f6d84a0381c0e4766388fcb..a8257c8f183f2c51e7888d70b9cc3d291958da2a 100644
--- a/cc/layers/layer_impl.cc
+++ b/cc/layers/layer_impl.cc
@@ -132,6 +132,9 @@ LayerImpl::~LayerImpl() {
   layer_tree_impl_->UnregisterScrollLayer(this);
   layer_tree_impl_->UnregisterLayer(this);
 
+  if (element_id_)
+    layer_tree_impl_->RemoveFromElementMap(this);
+
   TRACE_EVENT_OBJECT_DELETED_WITH_ID(
       TRACE_DISABLED_BY_DEFAULT("cc.debug"), "cc::LayerImpl", this);
 }
@@ -1242,7 +1245,11 @@ void LayerImpl::SetElementId(uint64_t element_id) {
   TRACE_EVENT1(TRACE_DISABLED_BY_DEFAULT("compositor-worker"),
                "LayerImpl::SetElementId", "id", element_id);
 
+  if (element_id_)
+    layer_tree_impl_->RemoveFromElementMap(this);
   element_id_ = element_id;
+  if (element_id_)
+    layer_tree_impl_->AddToElementMap(this);
   SetNeedsPushProperties();
 }
 
@@ -1254,6 +1261,8 @@ void LayerImpl::SetMutableProperties(uint32_t properties) {
                "LayerImpl::SetMutableProperties", "properties", properties);
 
   mutable_properties_ = properties;
+  if (element_id_)
+    layer_tree_impl_->AddToElementMap(this);
   SetNeedsPushProperties();
 }
 
@@ -1545,6 +1554,11 @@ void LayerImpl::UpdatePropertyTreeScrollOffset() {
 }
 
 void LayerImpl::DidUpdateScrollOffset() {
+  TRACE_EVENT2("compositor-worker,scroll-compensation",
+               "LayerImpl::DidUpdateScrollOffset", "x",
+               scroll_offset_->Current(IsActive()).x(), "y",
+               scroll_offset_->Current(IsActive()).y());
+
   DCHECK(scroll_offset_);
 
   layer_tree_impl()->DidUpdateScrollState(id());