Plumb phase/momentum for WheelEvent.

third_party/WebKit/public/platform/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 374 matching lines @@
         , movementY(0)
         , clickCount(0)
     {
     }
 };
 
 // WebMouseWheelEvent ---------------------------------------------------------
 
 class WebMouseWheelEvent : public WebMouseEvent {
 public:
+    // Note: due to the use of static_casts to convert this type to
+    // PlatformWheelEventPhase, and WheelEventPhase to
+    // WebMouseWheelEvent::Phase, the definition that follows must be kept in
+    // sync with that used for the corresponding types.

[esprehn, 2016/08/09 19:14:12]

We usually use static_asserts to enforce parallel enums.

     enum Phase {
         PhaseNone        = 0,
         PhaseBegan       = 1 << 0,
         PhaseStationary  = 1 << 1,
         PhaseChanged     = 1 << 2,
         PhaseEnded       = 1 << 3,
         PhaseCancelled   = 1 << 4,
         PhaseMayBegin    = 1 << 5,
     };
 
@@ skipping 251 matching lines @@
         , uniqueTouchEventId(0)
     {
     }
 };
 
 #pragma pack(pop)
 
 } // namespace blink
 
 #endif