Adopt "QuickScale" double-tap drag zoom code in the GestureProvider

ui/events/gesture_detection/gesture_config_helper_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_config_helper.h"
 
 #include "ui/gfx/android/view_configuration.h"
 #include "ui/gfx/screen.h"
 
 using gfx::ViewConfiguration;
@@ skipping 19 matching lines @@
   config.scaled_maximum_fling_velocity =
       ViewConfiguration::GetMaximumFlingVelocityInPixelsPerSecond();
 
   return config;
 }
 
 ScaleGestureDetector::Config DefaultScaleGestureDetectorConfig() {
   ScaleGestureDetector::Config config;
 
   config.gesture_detector_config = DefaultGestureDetectorConfig();
-  // TODO(jdduke): Enable "quick scale" on the ScaleGestureDetector, and remove
-  // corresponding double tap drag zoom code from GestureProvider, crbug/331092.
-  config.quick_scale_enabled = false;
+  config.quick_scale_enabled = true;
   config.min_scaling_touch_major =
       ViewConfiguration::GetMinScalingTouchMajorInPixels();
   config.min_scaling_span = ViewConfiguration::GetMinScalingSpanInPixels();
 
   return config;
 }
 
 SnapScrollController::Config DefaultSnapScrollControllerConfig() {
   SnapScrollController::Config config;
 
   const gfx::Display& display =
       gfx::Screen::GetNativeScreen()->GetPrimaryDisplay();
 
   config.screen_width_pixels = display.GetSizeInPixel().width();
   config.screen_height_pixels = display.GetSizeInPixel().height();
   config.device_scale_factor = display.device_scale_factor();
 
   return config;
 }
 
 GestureProvider::Config DefaultGestureProviderConfig() {
   GestureProvider::Config config;
   config.gesture_detector_config = DefaultGestureDetectorConfig();
   config.scale_gesture_detector_config = DefaultScaleGestureDetectorConfig();
   config.snap_scroll_controller_config = DefaultSnapScrollControllerConfig();
   return config;
 }
 
 }  // namespace ui