Add rails to input wheel events.

Source/platform/PlatformWheelEvent.h

 /*
  * Copyright (C) 2004, 2005, 2006, 2009 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 23 matching lines @@
 // Wheel events come in two flavors:
 // The ScrollByPixelWheelEvent is a fine-grained event that specifies the precise number of pixels to scroll. It is sent directly by MacBook touchpads on OS X,
 // and synthesized in other cases where platforms generate line-by-line scrolling events.
 // The ScrollByPageWheelEvent indicates that the wheel event should scroll an entire page. In this case WebCore's built in paging behavior is used to page
 // up and down (you get the same behavior as if the user was clicking in a scrollbar track to page up or page down).
 enum PlatformWheelEventGranularity {
     ScrollByPageWheelEvent,
     ScrollByPixelWheelEvent,
 };
 
+enum PlatformWheelEventRailMode {
+    PlatformWheelEventRailModeFree       = 0,
+    PlatformWheelEventRailModeHorizontal = 1 << 0,
+    PlatformWheelEventRailModeVertical   = 1 << 1,
+};
+
 #if OS(MACOSX)
 enum PlatformWheelEventPhase {
     PlatformWheelEventPhaseNone        = 0,
     PlatformWheelEventPhaseBegan       = 1 << 0,
     PlatformWheelEventPhaseStationary  = 1 << 1,
     PlatformWheelEventPhaseChanged     = 1 << 2,
     PlatformWheelEventPhaseEnded       = 1 << 3,
     PlatformWheelEventPhaseCancelled   = 1 << 4,
     PlatformWheelEventPhaseMayBegin    = 1 << 5,
 };
 #endif
 
 class PlatformWheelEvent : public PlatformEvent {
 public:
     PlatformWheelEvent()
         : PlatformEvent(PlatformEvent::Wheel)
         , m_deltaX(0)
         , m_deltaY(0)
         , m_wheelTicksX(0)
         , m_wheelTicksY(0)
         , m_granularity(ScrollByPixelWheelEvent)
         , m_hasPreciseScrollingDeltas(false)
         , m_canScroll(true)
+        , m_railMode(PlatformWheelEventRailModeFree)
 #if OS(MACOSX)
         , m_phase(PlatformWheelEventPhaseNone)
         , m_momentumPhase(PlatformWheelEventPhaseNone)
         , m_canRubberbandLeft(true)
         , m_canRubberbandRight(true)
 #endif
     {
     }
 
     PlatformWheelEvent(IntPoint position, IntPoint globalPosition, float deltaX, float deltaY, float wheelTicksX, float wheelTicksY, PlatformWheelEventGranularity granularity, bool shiftKey, bool ctrlKey, bool altKey, bool metaKey)
         : PlatformEvent(PlatformEvent::Wheel, shiftKey, ctrlKey, altKey, metaKey, 0)
         , m_position(position)
         , m_globalPosition(globalPosition)
         , m_deltaX(deltaX)
         , m_deltaY(deltaY)
         , m_wheelTicksX(wheelTicksX)
         , m_wheelTicksY(wheelTicksY)
         , m_granularity(granularity)
         , m_hasPreciseScrollingDeltas(false)
         , m_canScroll(true)
+        , m_railMode(PlatformWheelEventRailModeFree)
 #if OS(MACOSX)
         , m_phase(PlatformWheelEventPhaseNone)
         , m_momentumPhase(PlatformWheelEventPhaseNone)
         , m_canRubberbandLeft(true)
         , m_canRubberbandRight(true)
 #endif
     {
     }
 
     const IntPoint& position() const { return m_position; } // PlatformWindow coordinates.
     const IntPoint& globalPosition() const { return m_globalPosition; } // Screen coordinates.
 
     float deltaX() const { return m_deltaX; }
     float deltaY() const { return m_deltaY; }
 
     float wheelTicksX() const { return m_wheelTicksX; }
     float wheelTicksY() const { return m_wheelTicksY; }
 
     PlatformWheelEventGranularity granularity() const { return m_granularity; }
 
     bool hasPreciseScrollingDeltas() const { return m_hasPreciseScrollingDeltas; }
     void setHasPreciseScrollingDeltas(bool b) { m_hasPreciseScrollingDeltas = b; }
     bool canScroll() const { return m_canScroll; }
     void setCanScroll(bool b) { m_canScroll = b; }
+    PlatformWheelEventRailMode railMode() const { return m_railMode; }
+
 #if OS(MACOSX)
     PlatformWheelEventPhase phase() const { return m_phase; }
     PlatformWheelEventPhase momentumPhase() const { return m_momentumPhase; }
     bool useLatchedEventNode() const { return m_momentumPhase == PlatformWheelEventPhaseBegan || m_momentumPhase == PlatformWheelEventPhaseChanged; }
     bool canRubberbandLeft() const { return m_canRubberbandLeft; }
     bool canRubberbandRight() const { return m_canRubberbandRight; }
 #else
     bool useLatchedEventNode() const { return false; }
 #endif
 
 protected:
     IntPoint m_position;
     IntPoint m_globalPosition;
     float m_deltaX;
     float m_deltaY;
     float m_wheelTicksX;
     float m_wheelTicksY;
     PlatformWheelEventGranularity m_granularity;
     bool m_hasPreciseScrollingDeltas;
     bool m_canScroll;
+    PlatformWheelEventRailMode m_railMode;
 #if OS(MACOSX)
     PlatformWheelEventPhase m_phase;
     PlatformWheelEventPhase m_momentumPhase;
     bool m_canRubberbandLeft;
     bool m_canRubberbandRight;
 #endif
 };
 
 } // namespace blink
 
 #endif // PlatformWheelEvent_h