Replace layer id with Element id for tracking scrollbar animation controllers

cc/layers/layer.cc

 // Copyright 2010 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.
 
 #include "cc/layers/layer.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <algorithm>
@@ skipping 1111 matching lines @@
 
 void Layer::PushPropertiesTo(LayerImpl* layer) {
   TRACE_EVENT0("cc", "Layer::PushPropertiesTo");
   DCHECK(layer_tree_host_);
 
   // If we did not SavePaintProperties() for the layer this frame, then push the
   // real property values, not the paint property values.
   bool use_paint_properties = paint_properties_.source_frame_number ==
                               layer_tree_host_->SourceFrameNumber();
 
+  // The ElementId should be set first because other setters depend on it such
+  // as LayerImpl::SetScrollClipLayer.
+  layer->SetElementId(inputs_.element_id);
   layer->SetBackgroundColor(inputs_.background_color);
   layer->SetSafeOpaqueBackgroundColor(safe_opaque_background_color_);
   layer->SetBounds(use_paint_properties ? paint_properties_.bounds
                                         : inputs_.bounds);
 
 #if defined(NDEBUG)
   if (frame_viewer_instrumentation::IsTracingLayerTreeSnapshots())
     layer->SetDebugInfo(TakeDebugInfo());
 #else
   layer->SetDebugInfo(TakeDebugInfo());
@@ skipping 20 matching lines @@
   layer->set_should_flatten_transform_from_property_tree(
       should_flatten_transform_from_property_tree_);
   layer->SetUseParentBackfaceVisibility(inputs_.use_parent_backface_visibility);
   layer->SetUseLocalTransformForBackfaceVisibility(
       use_local_transform_for_backface_visibility_);
   layer->SetShouldCheckBackfaceVisibility(should_check_backface_visibility_);
 
   layer->SetScrollClipLayer(inputs_.scroll_clip_layer_id);
   layer->set_user_scrollable_horizontal(inputs_.user_scrollable_horizontal);
   layer->set_user_scrollable_vertical(inputs_.user_scrollable_vertical);
-  layer->SetElementId(inputs_.element_id);
   layer->SetMutableProperties(inputs_.mutable_properties);
 
   // When a scroll offset animation is interrupted the new scroll position on
   // the pending tree will clobber any impl-side scrolling occuring on the
   // active tree. To do so, avoid scrolling the pending tree along with it
   // instead of trying to undo that scrolling later.
   if (ScrollOffsetAnimationWasInterrupted())
     layer->layer_tree_impl()
         ->property_trees()
         ->scroll_tree.SetScrollOffsetClobberActiveValue(layer->id());
@@ skipping 259 matching lines @@
       ->num_copy_requests_in_subtree;
 }
 
 gfx::Transform Layer::ScreenSpaceTransform() const {
   DCHECK_NE(transform_tree_index_, TransformTree::kInvalidNodeId);
   return draw_property_utils::ScreenSpaceTransform(
       this, layer_tree_host_->property_trees()->transform_tree);
 }
 
 }  // namespace cc