Remove abstract Clone and Cancel methods from MotionEvent

ui/events/gesture_detection/motion_event_generic.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_DETECTION_UI_MOTION_EVENT_GENERIC_H_
 #define UI_EVENTS_GESTURE_DETECTION_UI_MOTION_EVENT_GENERIC_H_
 
 #include "base/basictypes.h"
 #include "base/containers/stack_container.h"
+#include "base/memory/scoped_vector.h"
 #include "ui/events/gesture_detection/gesture_detection_export.h"
 #include "ui/events/gesture_detection/motion_event.h"
 
 namespace ui {
 
 struct GESTURE_DETECTION_EXPORT PointerProperties {
   PointerProperties();
-  PointerProperties(float x, float y);
+  PointerProperties(float x, float y, float touch_major);
+  PointerProperties(const MotionEvent& event, size_t pointer_index);
 
   int id;
   MotionEvent::ToolType tool_type;
   float x;
   float y;
   float raw_x;
   float raw_y;
   float pressure;
   float touch_major;
   float touch_minor;
   float orientation;
 };
 
 // A generic MotionEvent implementation.
 class GESTURE_DETECTION_EXPORT MotionEventGeneric : public MotionEvent {
  public:
   MotionEventGeneric(Action action,
                      base::TimeTicks event_time,
                      const PointerProperties& pointer);
-  MotionEventGeneric(const MotionEventGeneric& other);
+  MotionEventGeneric(const MotionEventGeneric& event);
 
   virtual ~MotionEventGeneric();
 
   // MotionEvent implementation.
   virtual int GetId() const override;
   virtual Action GetAction() const override;
   virtual int GetActionIndex() const override;
   virtual size_t GetPointerCount() const override;
   virtual int GetPointerId(size_t pointer_index) const override;
   virtual float GetX(size_t pointer_index) const override;
   virtual float GetY(size_t pointer_index) const override;
   virtual float GetRawX(size_t pointer_index) const override;
   virtual float GetRawY(size_t pointer_index) const override;
   virtual float GetTouchMajor(size_t pointer_index) const override;
   virtual float GetTouchMinor(size_t pointer_index) const override;
   virtual float GetOrientation(size_t pointer_index) const override;
   virtual float GetPressure(size_t pointer_index) const override;
   virtual ToolType GetToolType(size_t pointer_index) const override;
   virtual int GetButtonState() const override;
   virtual int GetFlags() const override;
   virtual base::TimeTicks GetEventTime() const override;
-  virtual scoped_ptr<MotionEvent> Clone() const override;
-  virtual scoped_ptr<MotionEvent> Cancel() const override;
+  virtual size_t GetHistorySize() const override;
+  virtual base::TimeTicks GetHistoricalEventTime(
+      size_t historical_index) const override;
+  virtual float GetHistoricalTouchMajor(size_t pointer_index,
+                                        size_t historical_index) const override;
+  virtual float GetHistoricalX(size_t pointer_index,
+                               size_t historical_index) const override;
+  virtual float GetHistoricalY(size_t pointer_index,
+                               size_t historical_index) const override;
 
   void PushPointer(const PointerProperties& pointer);
 
+  // Add an event to the history. Note that |event| must have the same
+  // pointer count, and must be of the same type (ACTION_MOVE), as this event.

[tdresser, 2014/10/20 15:19:15]

This is a little confusing.

Based on the code, perhaps: 

// Add an event to the history. Note that |this| and |event| must have the 
// same pointer count and must both have an action of ACTION_MOVE.

[jdduke (slow), 2014/10/21 22:19:58]

Done.

+  void PushHistoricalEvent(scoped_ptr<MotionEvent> event);
+
   void set_action(Action action) { action_ = action; }
   void set_event_time(base::TimeTicks event_time) { event_time_ = event_time; }
   void set_id(int id) { id_ = id; }
   void set_action_index(int action_index) { action_index_ = action_index; }
   void set_button_state(int button_state) { button_state_ = button_state; }
   void set_flags(int flags) { flags_ = flags; }
 
+  static scoped_ptr<MotionEventGeneric> CloneEvent(const MotionEvent& event);
+  static scoped_ptr<MotionEventGeneric> CancelEvent(const MotionEvent& event);
+
  protected:
   MotionEventGeneric();
+  MotionEventGeneric(const MotionEvent& event, bool with_history);
+  MotionEventGeneric& operator=(const MotionEventGeneric& other);
 
   void PopPointer();
 
   PointerProperties& pointer(size_t index) { return pointers_[index]; }
   const PointerProperties& pointer(size_t index) const {
     return pointers_[index];
   }
 
  private:
   enum { kTypicalMaxPointerCount = 5 };
 
   Action action_;
   base::TimeTicks event_time_;
   int id_;
   int action_index_;
   int button_state_;
   int flags_;
   base::StackVector<PointerProperties, kTypicalMaxPointerCount> pointers_;
+  ScopedVector<MotionEvent> historical_events_;
 };
 
 }  // namespace ui
 
 #endif  // UI_EVENTS_GESTURE_DETECTION_UI_MOTION_EVENT_GENERIC_H_