[cc] Remove unused parameter to DidUpdateScrollOffset

cc/trees/layer_tree_impl.cc

 // Copyright 2011 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/trees/layer_tree_impl.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <algorithm>
@@ skipping 129 matching lines @@
   if (OuterViewportContainerLayer() &&
       id == OuterViewportContainerLayer()->id())
     return true;
 
   return false;
 }
 
 // TODO(sunxd): when we have a layer_id to property_tree index map in property
 // trees, use the transform_id parameter instead of looking for indices from
 // LayerImpls.
-void LayerTreeImpl::DidUpdateScrollOffset(int layer_id, int transform_id) {
+void LayerTreeImpl::DidUpdateScrollOffset(int layer_id) {
   DidUpdateScrollState(layer_id);
   TransformTree& transform_tree = property_trees()->transform_tree;
   ScrollTree& scroll_tree = property_trees()->scroll_tree;
+  int transform_id = -1;
 
   // If pending tree topology changed and we still want to notify the pending
   // tree about scroll offset in the active tree, we may not find the
   // corresponding pending layer.
   if (LayerById(layer_id)) {
     transform_id = LayerById(layer_id)->transform_tree_index();

[sunxd, 2016/09/16 14:34:57]

Maybe we can move the TODO above here. As transform_id is now retrieved in the
function.

[Ian Vollick, 2016/09/16 15:09:44]

Done.

   } else {
     DCHECK(!IsActiveTree());
     return;
   }
 
   if (transform_id != -1) {
     TransformNode* node = transform_tree.Node(transform_id);
     if (node->scroll_offset != scroll_tree.current_scroll_offset(layer_id)) {
       node->scroll_offset = scroll_tree.current_scroll_offset(layer_id);
       node->needs_local_transform_update = true;
       transform_tree.set_needs_update(true);
     }
     node->transform_changed = true;
     property_trees()->changed = true;
     set_needs_update_draw_properties();
   }
 
   if (IsActiveTree() && layer_tree_host_impl_->pending_tree())
-    layer_tree_host_impl_->pending_tree()->DidUpdateScrollOffset(layer_id,
-                                                                 transform_id);
+    layer_tree_host_impl_->pending_tree()->DidUpdateScrollOffset(layer_id);
 }
 
 void LayerTreeImpl::DidUpdateScrollState(int layer_id) {
   if (!IsActiveTree())
     return;
 
   if (layer_id == Layer::INVALID_ID)
     return;
 
   int scroll_layer_id, clip_layer_id;
@@ skipping 1882 matching lines @@
 
 void LayerTreeImpl::ResetAllChangeTracking() {
   layers_that_should_push_properties_.clear();
   // Iterate over all layers, including masks and replicas.
   for (auto& layer : *layers_)
     layer->ResetChangeTracking();
   property_trees_.ResetAllChangeTracking();
 }
 
 }  // namespace cc