Make touch-based synthetic gesture take touch slop into account.

content/browser/renderer_host/input/synthetic_smooth_scroll_gesture.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_smooth_scroll_gesture.h"
 
 #include <cmath>
 
 #include "content/common/input/input_event.h"
 #include "ui/events/latency_info.h"
@@ skipping 32 matching lines @@
 
   return (state_ == DONE) ? SyntheticGesture::GESTURE_FINISHED
                           : SyntheticGesture::GESTURE_RUNNING;
 }
 
 void SyntheticSmoothScrollGesture::ForwardTouchInputEvents(
     const base::TimeDelta& interval, SyntheticGestureTarget* target) {
   switch (state_) {
     case STARTED:
       // Check for an early finish.
-      if (HasScrolledEntireDistance()) {
+      if (params_.distance == 0) {
         state_ = DONE;
         break;
       }
+      if (params_.distance > 0)
+        params_.distance += target->GetTouchSlopInDips();
+      else
+        params_.distance -= target->GetTouchSlopInDips();
       touch_event_.PressPoint(params_.anchor.x(), current_y_);
       ForwardTouchEvent(target);
       state_ = MOVING;
       break;
     case MOVING:
       current_y_ += GetPositionDelta(interval);
       touch_event_.MovePoint(0, params_.anchor.x(), current_y_);
       ForwardTouchEvent(target);
 
       if (HasScrolledEntireDistance())
@@ skipping 89 matching lines @@
       params_.distance > 0 ? remaining_distance : -remaining_distance;
   DCHECK_GE(abs_remaining_distance, 0);
   return abs_remaining_distance;
 }
 
 bool SyntheticSmoothScrollGesture::HasScrolledEntireDistance() const {
   return ComputeAbsoluteRemainingDistance() == 0;
 }
 
 }  // namespace content