Tweak the aura gesture recognizer slightly.

ui/aura/gestures/gesture_point.cc

 // Copyright (c) 2012 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/aura/gestures/gesture_point.h"
 
 #include "ui/aura/event.h"
 #include "ui/base/events.h"
 
 namespace {
@@ skipping 67 matching lines @@
 
 bool GesturePoint::IsInScrollWindow(const TouchEvent& event) const {
   return event.type() == ui::ET_TOUCH_MOVED &&
          !IsInsideManhattanSquare(event);
 }
 
 bool GesturePoint::IsInFlickWindow(const TouchEvent& event) const {
   return IsOverMinFlickSpeed() && event.type() != ui::ET_TOUCH_CANCELLED;
 }
 
+bool GesturePoint::DidScroll(const TouchEvent& event) const {
+  return abs(last_touch_position_.x() - first_touch_position_.x()) > 0 ||
+         abs(last_touch_position_.y() - first_touch_position_.y()) > 0;
+}
+
 bool GesturePoint::IsInClickTimeWindow() const {
   double duration = last_touch_time_ - first_touch_time_;
   return duration >= kMinimumTouchDownDurationInSecondsForClick &&
          duration < kMaximumTouchDownDurationInSecondsForClick;
 }
 
 bool GesturePoint::IsInSecondClickTimeWindow() const {
   double duration =  last_touch_time_ - last_tap_time_;
   return duration < kMaximumSecondsBetweenDoubleClick;
 }
@@ skipping 10 matching lines @@
                           abs(event.y() - last_tap_position_.y());
   return manhattanDistance < kMaximumTouchMoveInPixelsForClick;
 }
 
 bool GesturePoint::IsOverMinFlickSpeed() const {
   return (x_velocity_ * x_velocity_ + y_velocity_ * y_velocity_) >
           kMinFlickSpeedSquared;
 }
 
 }  // namespace aura