First Implementation of Snapped Points

ui/events/gesture_curve.h

 // 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.
 
 #ifndef UI_EVENTS_GESTURE_CURVE_H_
 #define UI_EVENTS_GESTURE_CURVE_H_
 
 #include "base/time/time.h"
 #include "ui/gfx/geometry/vector2d_f.h"
 
 namespace ui {
 
 // An abstraction of curve-based gesture motion, allowing platform-specific
 // motion tailoring.
 class EVENTS_BASE_EXPORT GestureCurve {
  public:
   virtual ~GestureCurve() {}
 
   // The output |offset| represents the total movement of the curve from its
   // start until |time|.
   // The output |velocity| represents the instantenous velocity at |time|.
   // Returns false if |time| exceeds the fling duration, in which case
   // the terminal offset will be reported.
   virtual bool ComputeScrollOffset(base::TimeTicks time,
                                    gfx::Vector2dF* offset,
                                    gfx::Vector2dF* velocity) = 0;
+
+  virtual void ComputeTotalScrollOffset(gfx::Vector2dF& offset) = 0;
+
+  virtual bool ResetCurveBySnappedOffset(const gfx::Vector2dF& offset) = 0;
 };
 
 }  // namespace ui
 
 #endif  // UI_EVENTS_GESTURE_CURVE_H_