cc: Add checker-imaging support to TileManager.

cc/tiles/tile_manager_settings.h

+// Copyright 2017 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_TILES_TILE_MANAGER_SETTINGS_H_
+#define CC_TILES_TILE_MANAGER_SETTINGS_H_
+
+#include "cc/base/cc_export.h"
+
+namespace cc {
+
+struct CC_EXPORT TileManagerSettings {
+  bool use_partial_raster = false;
+  bool check_tile_priority_inversion = false;
+  bool enable_checker_imaging = false;
+};
+
+}  // namespace cc
+
+#endif  // CC_TILES_TILE_MANAGER_SETTINGS_H_