Gesture recognition constants should all be stored in the GestureConfiguration object.

ui/aura/gestures/gesture_configuration.cc

 // Copyright (c) 2012 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 "ui/aura/gestures/gesture_configuration.h"
 
 namespace aura {
 
+// Ordered alphabetically ignoring underscores, to align with the
+// associated list of prefs in gesture_prefs_aura.cc.
+double GestureConfiguration::long_press_time_in_seconds_ = 0.5;
+double GestureConfiguration::max_seconds_between_double_click_ = 0.7;
+double
+  GestureConfiguration::max_separation_for_gesture_touches_in_pixels_ = 150;
 double
   GestureConfiguration::max_touch_down_duration_in_seconds_for_click_ = 0.8;
+double GestureConfiguration::max_touch_move_in_pixels_for_click_ = 20;
+double GestureConfiguration::min_distance_for_pinch_scroll_in_pixels_ = 20;
+double GestureConfiguration::min_flick_speed_squared_ = 550.f * 550.f;
+double GestureConfiguration::min_pinch_update_distance_in_pixels_ = 5;
+double GestureConfiguration::min_rail_break_velocity_ = 200;
+double GestureConfiguration::min_scroll_delta_squared_ = 5 * 5;
 double
   GestureConfiguration::min_touch_down_duration_in_seconds_for_click_ = 0.01;
-double GestureConfiguration::max_seconds_between_double_click_ = 0.7;
-double GestureConfiguration::max_touch_move_in_pixels_for_click_ = 20;
-double GestureConfiguration::min_flick_speed_squared_ = 550.f * 550.f;
-double GestureConfiguration::minimum_pinch_update_distance_in_pixels_ = 5;
-double GestureConfiguration::minimum_distance_for_pinch_scroll_in_pixels_ = 20;
-int GestureConfiguration::max_separation_for_gesture_touches_in_pixels_ = 150;
+
+// The number of points used in the linear regression which determines
+// touch velocity. If fewer than this number of points have been seen,
+// velocity is reported as 0.
+int GestureConfiguration::points_buffered_for_velocity_ = 10;
+double GestureConfiguration::rail_break_proportion_ = 15;
+double GestureConfiguration::rail_start_proportion_ = 2;
 
 }  // namespace aura