Eager Gesture Recognition on Aura

ui/events/gesture_detection/gesture_config_helper_aura.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_config_helper.h"
 
 #include <cmath>
@@ skipping 49 matching lines @@
   config.min_scaling_touch_major = GestureConfiguration::default_radius() * 2;
   config.min_scaling_span = GestureConfiguration::min_scaling_span_in_pixels();
   config.min_pinch_update_span_delta = min_pinch_update_distance;
   return config;
 }
 
 }  // namespace
 
 GestureProvider::Config DefaultGestureProviderConfig() {
   GestureProvider::Config config;
-  config.display = gfx::Screen::GetNativeScreen()->GetPrimaryDisplay();
+  gfx::Screen* screen = gfx::Screen::GetScreenByType(gfx::SCREEN_TYPE_NATIVE);
+  // |screen| is sometimes NULL during tests.

[jdduke (slow), 2014/07/31 16:19:03]

Hmm, I wonder if it would be an improvement to have Display be an argument to
this function? Maybe some other day... (actually I'd like to get rid of the
Display dependency entirely but that's for another day...).

+  if (screen)
+    config.display = screen->GetPrimaryDisplay();
   config.gesture_detector_config = DefaultGestureDetectorConfig();
   config.scale_gesture_detector_config = DefaultScaleGestureDetectorConfig();
   config.gesture_begin_end_types_enabled = true;
   // Half the size of the default touch length is a reasonable minimum.
   config.min_gesture_bounds_length = GestureConfiguration::default_radius();
   return config;
 }
 
 }  // namespace ui