Remove abstract Clone and Cancel methods from MotionEvent

ui/events/gesture_detection/motion_event_generic.h

Index: ui/events/gesture_detection/motion_event_generic.h
diff --git a/ui/events/gesture_detection/motion_event_generic.h b/ui/events/gesture_detection/motion_event_generic.h
index 41911c1b868e04453cbc46f40eced7cb6372fde8..ff355656ae0fb6ceee6492eae5aae42c9da9cdf2 100644
--- a/ui/events/gesture_detection/motion_event_generic.h
+++ b/ui/events/gesture_detection/motion_event_generic.h
@@ -7,6 +7,7 @@
 
 #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"
 
@@ -14,7 +15,8 @@ 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;
@@ -34,7 +36,7 @@ class GESTURE_DETECTION_EXPORT MotionEventGeneric : public MotionEvent {
   MotionEventGeneric(Action action,
                      base::TimeTicks event_time,
                      const PointerProperties& pointer);
-  MotionEventGeneric(const MotionEventGeneric& other);
+  MotionEventGeneric(const MotionEventGeneric& event);
 
   virtual ~MotionEventGeneric();
 
@@ -56,11 +58,22 @@ class GESTURE_DETECTION_EXPORT MotionEventGeneric : public MotionEvent {
   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; }
@@ -68,8 +81,13 @@ class GESTURE_DETECTION_EXPORT MotionEventGeneric : public MotionEvent {
   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();
 
@@ -88,6 +106,7 @@ class GESTURE_DETECTION_EXPORT MotionEventGeneric : public MotionEvent {
   int button_state_;
   int flags_;
   base::StackVector<PointerProperties, kTypicalMaxPointerCount> pointers_;
+  ScopedVector<MotionEvent> historical_events_;
 };
 
 }  // namespace ui