Implement scroll handler latency tracking

cc/trees/layer_tree_host_common.h

 // 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.
 
 #ifndef CC_TREES_LAYER_TREE_HOST_COMMON_H_
 #define CC_TREES_LAYER_TREE_HOST_COMMON_H_
 
 #include <limits>
 #include <vector>
 
 #include "base/bind.h"
 #include "base/memory/ref_counted.h"
 #include "cc/base/cc_export.h"
 #include "cc/base/scoped_ptr_vector.h"
 #include "cc/layers/layer_lists.h"
 #include "ui/gfx/rect.h"
 #include "ui/gfx/transform.h"
 #include "ui/gfx/vector2d.h"
 
+namespace ui {
+struct LatencyInfo;
+}
+
 namespace cc {
 
 class LayerImpl;
 class Layer;
 
 class CC_EXPORT LayerTreeHostCommon {
  public:
   static gfx::Rect CalculateVisibleRect(const gfx::Rect& target_surface_rect,
                                         const gfx::Rect& layer_bound_rect,
                                         const gfx::Transform& transform);
@@ skipping 102 matching lines @@
     gfx::Vector2d scroll_delta;
   };
 };
 
 struct CC_EXPORT ScrollAndScaleSet {
   ScrollAndScaleSet();
   ~ScrollAndScaleSet();
 
   std::vector<LayerTreeHostCommon::ScrollUpdateInfo> scrolls;
   float page_scale_delta;
+  std::vector<ui::LatencyInfo> latency_infos;
 };
 
 template <typename LayerType>
 bool LayerTreeHostCommon::RenderSurfaceContributesToTarget(
     LayerType* layer,
     int target_surface_layer_id) {
   // A layer will either contribute its own content, or its render surface's
   // content, to the target surface. The layer contributes its surface's content
   // when both the following are true:
   //  (1) The layer actually has a render surface, and
@@ skipping 93 matching lines @@
           false,
           render_surface_layer_list,
           0) {
   DCHECK(root_layer);
   DCHECK(render_surface_layer_list);
 }
 
 }  // namespace cc
 
 #endif  // CC_TREES_LAYER_TREE_HOST_COMMON_H_