Expose double-tap platform support via ui::GestureConfiguration

ui/events/gesture_detection/gesture_configuration_android.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 "ui/events/gesture_detection/gesture_configuration.h"
 
 #include "ui/gfx/android/view_configuration.h"
 #include "ui/gfx/screen.h"
 
 using gfx::ViewConfiguration;
@@ skipping 15 matching lines @@
 
   static GestureConfigurationAndroid* GetInstance() {
     return Singleton<GestureConfigurationAndroid>::get();
   }
 
  private:
   GestureConfigurationAndroid() : GestureConfiguration() {
     float raw_pixel_to_dip_ratio = 1.f / gfx::Screen::GetNativeScreen()
                                        ->GetPrimaryDisplay()
                                        .device_scale_factor();
+    set_double_tap_enabled(true);
     set_double_tap_timeout_in_ms(ViewConfiguration::GetDoubleTapTimeoutInMs());
     set_gesture_begin_end_types_enabled(false);
     set_long_press_time_in_ms(ViewConfiguration::GetLongPressTimeoutInMs());
     set_max_distance_between_taps_for_double_tap(
         ViewConfiguration::GetDoubleTapSlopInPixels() * raw_pixel_to_dip_ratio);
     set_max_fling_velocity(
         ViewConfiguration::GetMaximumFlingVelocityInPixelsPerSecond() *
         raw_pixel_to_dip_ratio);
     set_max_gesture_bounds_length(kMaxGestureBoundsLengthDips);
     set_max_touch_move_in_pixels_for_click(
@@ skipping 19 matching lines @@
 };
 
 }  // namespace
 
 // Create a GestureConfigurationAura singleton instance when using Android.
 GestureConfiguration* GestureConfiguration::GetInstance() {
   return GestureConfigurationAndroid::GetInstance();
 }
 
 }  // namespace ui