Add canScroll bit to WebMouseWheelEvent

public/web/WebInputEvent.h

 /*
  * Copyright (C) 2009 Google 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 356 matching lines @@
     // These flags prevent rubber banding from starting in a given direction,
     // but have no effect on an ongoing rubber banding. A rubber banding that
     // started in the vertical direction is allowed to continue in the right
     // direction, even if canRubberbandRight is 0.
     bool canRubberbandLeft;
     bool canRubberbandRight;
 
     bool scrollByPage;
     bool hasPreciseScrollingDeltas;
 
+    // When false, this wheel event should not trigger scrolling (or any other default
+    // action) if the event goes unhandled by JavaScript. This is used, for example,
+    // when the browser decides the default behavior for Ctrl+Wheel should be to zoom
+    // instead of scroll.
+    bool canScroll;
+
     WebMouseWheelEvent()
         : WebMouseEvent(sizeof(WebMouseWheelEvent))
         , deltaX(0.0f)
         , deltaY(0.0f)
         , wheelTicksX(0.0f)
         , wheelTicksY(0.0f)
         , accelerationRatioX(1.0f)
         , accelerationRatioY(1.0f)
         , phase(PhaseNone)
         , momentumPhase(PhaseNone)
         , canRubberbandLeft(true)
         , canRubberbandRight(true)
         , scrollByPage(false)
         , hasPreciseScrollingDeltas(false)
+        , canScroll(true)
     {
     }
 };
 
 // WebGestureEvent --------------------------------------------------------------
 
 class WebGestureEvent : public WebInputEvent {
 public:
     int x;
     int y;
@@ skipping 102 matching lines @@
         , causesScrollingIfUncanceled(false)
     {
     }
 };
 
 #pragma pack(pop)
 
 } // namespace blink
 
 #endif