[Aura] Reduce frequency of PinchUpdate events.

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 34 matching lines @@
 
   return config;
 }
 
 ScaleGestureDetector::Config DefaultScaleGestureDetectorConfig() {
   ScaleGestureDetector::Config config;
 
   config.gesture_detector_config = DefaultGestureDetectorConfig();
   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 =
+      GestureConfiguration::min_pinch_update_distance_in_pixels();
   return config;
 }
 
 }  // namespace
 
 GestureProvider::Config DefaultGestureProviderConfig() {
   GestureProvider::Config config;
   config.display = gfx::Screen::GetNativeScreen()->GetPrimaryDisplay();
   config.gesture_detector_config = DefaultGestureDetectorConfig();
   config.scale_gesture_detector_config = DefaultScaleGestureDetectorConfig();
   config.gesture_begin_end_types_enabled = true;
   return config;
 }
 
 }  // namespace ui