Synthetic pinch gesture take scale factor as parameter.

content/browser/renderer_host/input/synthetic_gesture_target_aura.cc

 // Copyright 2013 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 "content/browser/renderer_host/input/synthetic_gesture_target_aura.h"
 
 #include "content/browser/renderer_host/render_widget_host_impl.h"
 #include "content/browser/renderer_host/render_widget_host_view_aura.h"
 #include "content/browser/renderer_host/ui_events_helper.h"
 #include "ui/aura/window.h"
@@ skipping 120 matching lines @@
 SyntheticGestureTargetAura::GetDefaultSyntheticGestureSourceType() const {
   return SyntheticGestureParams::TOUCH_INPUT;
 }
 
 int SyntheticGestureTargetAura::GetTouchSlopInDips() const {
   // - 1 because Aura considers a pointer to be moving if it has moved at least
   // 'max_touch_move_in_pixels_for_click' pixels.
   return ui::GestureConfiguration::max_touch_move_in_pixels_for_click() - 1;
 }
 
+int SyntheticGestureTargetAura::GetMinScalingSpanInDips() const {
+  return ui::GestureConfiguration::min_distance_for_pinch_scroll_in_pixels();
+}
+
 aura::Window* SyntheticGestureTargetAura::GetWindow() const {
   aura::Window* window = render_widget_host()->GetView()->GetNativeView();
   DCHECK(window);
   return window;
 }
 
 }  // namespace content