Update from https://crrev.com/316786

cc/trees/occlusion.cc

 // Copyright 2014 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/occlusion.h"
 
 #include "cc/base/math_util.h"
 #include "ui/gfx/geometry/rect.h"
 
 namespace cc {
@@ skipping 67 matching lines @@
   // These subtract operations are more lossy than if we did both operations at
   // once.
   unoccluded_rect_in_target_surface.Subtract(
       occlusion_from_inside_target_.bounds());
   unoccluded_rect_in_target_surface.Subtract(
       occlusion_from_outside_target_.bounds());
 
   return unoccluded_rect_in_target_surface;
 }
 
+bool Occlusion::IsEqual(const Occlusion& other) const {
+  return draw_transform_ == other.draw_transform_ &&
+         occlusion_from_inside_target_ == other.occlusion_from_inside_target_ &&
+         occlusion_from_outside_target_ == other.occlusion_from_outside_target_;
+}
+
+std::string Occlusion::ToString() const {
+  return draw_transform_.ToString() + "outside(" +
+         occlusion_from_outside_target_.ToString() + ") inside(" +
+         occlusion_from_inside_target_.ToString() + ")";
+}
+
 }  // namespace cc