Expose native, desktop and mobile gesture detection defaults

ui/events/gesture_detection/gesture_detector.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.
 
 // MSVC++ requires this to be set before any other includes to get M_PI.
 #define _USE_MATH_DEFINES
 
 #include "ui/events/gesture_detection/gesture_detector.h"
 
 #include <cmath>
@@ skipping 20 matching lines @@
 enum TimeoutEvent {
   SHOW_PRESS = 0,
   LONG_PRESS,
   TAP,
   TIMEOUT_EVENT_COUNT
 };
 
 }  // namespace
 
 // Note: These constants were taken directly from the default (unscaled)
-// versions found in Android's ViewConfiguration.
+// versions found in Android's ViewConfiguration. Do not change these default
+// values without explicitly consulting an OWNER.
 GestureDetector::Config::Config()
     : longpress_timeout(base::TimeDelta::FromMilliseconds(500)),
       showpress_timeout(base::TimeDelta::FromMilliseconds(180)),
       double_tap_timeout(base::TimeDelta::FromMilliseconds(300)),
       double_tap_min_time(base::TimeDelta::FromMilliseconds(40)),
       touch_slop(8),
       double_tap_slop(100),
       minimum_fling_velocity(50),
       maximum_fling_velocity(8000),
       swipe_enabled(false),
@@ skipping 439 matching lines @@
     return false;
 
   if (vx_abs > vy_abs)
     vy = 0;
   else
     vx = 0;
   return listener_->OnSwipe(*current_down_event_, up, vx, vy);
 }
 
 }  // namespace ui