Add a MotionEventGeneric implementation

ui/events/gesture_detection/motion_event.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_MOTION_EVENT_H_
 #define UI_EVENTS_GESTURE_DETECTION_MOTION_EVENT_H_
 
 #include "base/memory/scoped_ptr.h"
 #include "base/time/time.h"
 #include "ui/events/gesture_detection/gesture_detection_export.h"
@@ skipping 39 matching lines @@
   // ACTION_POINTER_DOWN.
   virtual int GetActionIndex() const = 0;
   virtual size_t GetPointerCount() const = 0;
   virtual int GetPointerId(size_t pointer_index) const = 0;
   virtual float GetX(size_t pointer_index) const = 0;
   virtual float GetY(size_t pointer_index) const = 0;
   virtual float GetRawX(size_t pointer_index) const = 0;
   virtual float GetRawY(size_t pointer_index) const = 0;
   virtual float GetTouchMajor(size_t pointer_index) const = 0;
   virtual float GetPressure(size_t pointer_index) const = 0;
+  virtual ToolType GetToolType(size_t pointer_index) const = 0;
+  virtual int GetButtonState() const = 0;
   virtual base::TimeTicks GetEventTime() const = 0;
 
-  virtual size_t GetHistorySize() const = 0;
-  virtual base::TimeTicks GetHistoricalEventTime(
-      size_t historical_index) const = 0;
+  // Optional historical data, default implementation provides an empty history.
+  virtual size_t GetHistorySize() const;
+  virtual base::TimeTicks GetHistoricalEventTime(size_t historical_index) const;
   virtual float GetHistoricalTouchMajor(size_t pointer_index,
-                                        size_t historical_index) const = 0;
+                                        size_t historical_index) const;
   virtual float GetHistoricalX(size_t pointer_index,
-                               size_t historical_index) const = 0;
+                               size_t historical_index) const;
   virtual float GetHistoricalY(size_t pointer_index,
-                               size_t historical_index) const = 0;
-  virtual ToolType GetToolType(size_t pointer_index) const = 0;
-  virtual int GetButtonState() const = 0;
+                               size_t historical_index) const;
 
   virtual scoped_ptr<MotionEvent> Clone() const = 0;
   virtual scoped_ptr<MotionEvent> Cancel() const = 0;
 
   // Utility accessor methods for convenience.
   float GetX() const { return GetX(0); }
   float GetY() const { return GetY(0); }
   float GetRawX() const { return GetRawX(0); }
   float GetRawY() const { return GetRawY(0); }
   float GetRawOffsetX() const { return GetRawX() - GetX(); }
   float GetRawOffsetY() const { return GetRawY() - GetY(); }
   float GetTouchMajor() const { return GetTouchMajor(0); }
   float GetPressure() const { return GetPressure(0); }
 };
 
+GESTURE_DETECTION_EXPORT bool operator==(const MotionEvent& lhs,
+                                         const MotionEvent& rhs);
+GESTURE_DETECTION_EXPORT bool operator!=(const MotionEvent& lhs,
+                                         const MotionEvent& rhs);
+
 }  // namespace ui
 
 #endif  // UI_EVENTS_GESTURE_DETECTION_MOTION_EVENT_H_