Add impl/comp scrolling instrumentation.

cc/trees/layer_tree_host_common.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_host_common.h"
 
 #include <algorithm>
 
 #include "base/debug/trace_event.h"
 #include "cc/base/math_util.h"
 #include "cc/layers/heads_up_display_layer_impl.h"
 #include "cc/layers/layer.h"
 #include "cc/layers/layer_impl.h"
 #include "cc/layers/layer_iterator.h"
 #include "cc/layers/render_surface.h"
 #include "cc/layers/render_surface_impl.h"
 #include "cc/trees/layer_sorter.h"
 #include "cc/trees/layer_tree_impl.h"
 #include "ui/gfx/point_conversions.h"
 #include "ui/gfx/rect_conversions.h"
 #include "ui/gfx/transform.h"
 
 namespace cc {
 
 ScrollAndScaleSet::ScrollAndScaleSet() {}
 
 ScrollAndScaleSet::~ScrollAndScaleSet() {}
 
-static void SortLayers(LayerList::iterator forst,
+static void SortLayers(LayerList::iterator first,
                        LayerList::iterator end,
                        void* layer_sorter) {
   NOTREACHED();
 }
 
 static void SortLayers(LayerImplList::iterator first,
                        LayerImplList::iterator end,
                        LayerSorter* layer_sorter) {
   DCHECK(layer_sorter);
   TRACE_EVENT0("cc", "LayerTreeHostCommon::SortLayers");
@@ skipping 1847 matching lines @@
   // At this point, we think the point does hit the touch event handler region
   // on the layer, but we need to walk up the parents to ensure that the layer
   // was not clipped in such a way that the hit point actually should not hit
   // the layer.
   if (PointIsClippedBySurfaceOrClipRect(screen_space_point, layer_impl))
     return false;
 
   return true;
 }
 }  // namespace cc