Add gesture target fuzzing to views

ui/views/view_constants.h

 // Copyright (c) 2011 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.
 
 #ifndef UI_VIEWS_VIEW_CONSTANTS_H_
 #define UI_VIEWS_VIEW_CONSTANTS_H_
 
 #include "ui/views/views_export.h"
 
 namespace views {
 
 // Size (width or height) within which the user can hold the mouse and the
 // view should scroll.
 VIEWS_EXPORT extern const int kAutoscrollSize;
 
 // Time in milliseconds to autoscroll by a row. This is used during drag and
 // drop.
 VIEWS_EXPORT extern const int kAutoscrollRowTimerMS;
 
 // Used to determine whether a drop is on an item or before/after it. If a drop
 // occurs kDropBetweenPixels from the top/bottom it is considered before/after
 // the item, otherwise it is on the item.
 VIEWS_EXPORT extern const int kDropBetweenPixels;
 
+// A view will only be considered a candidate for touch fuzzing if the touch
+// region covers at least |kFuzzingOverlapPercentage| percent of the area of
+// the view's bounding rectangle.
+VIEWS_EXPORT extern const float kFuzzingOverlapPercentage;
+
 }  // namespace views
 
 #endif  // UI_VIEWS_VIEW_CONSTANTS_H_