Add wheel support to sky-scrollable

sky/engine/public/platform/WebInputEvent.h

Index: sky/engine/public/platform/WebInputEvent.h
diff --git a/sky/engine/public/platform/WebInputEvent.h b/sky/engine/public/platform/WebInputEvent.h
index 61cec7c9407974e36d3850f575558cefbd1cf039..ea2df82622f2ff0ebfb74f839d4aafbb39c49128 100644
--- a/sky/engine/public/platform/WebInputEvent.h
+++ b/sky/engine/public/platform/WebInputEvent.h
@@ -121,6 +121,8 @@ public:
         GesturePinchEnd,
         GesturePinchUpdate,
         GestureTypeLast = GesturePinchUpdate,
+
+        WheelEvent,
     };
 
     enum Modifiers {
@@ -170,18 +172,21 @@ public:
         return PointerTypeFirst <= type && type <= PointerTypeLast;
     }
 
-    // Returns true if the WebInputEvent |type| is a keyboard event.
     static bool isKeyboardEventType(int type)
     {
         return KeyboardTypeFirst <= type && type <= KeyboardTypeLast;
     }
 
-    // Returns true if the WebInputEvent is a gesture event.
     static bool isGestureEventType(int type)
     {
         return GestureTypeFirst <= type && type <= GestureTypeLast;
     }
 
+    static bool isWheelEventType(int type)
+    {
+        return type == WheelEvent;
+    }
+
 protected:
     explicit WebInputEvent(unsigned sizeParam)
     {
@@ -238,32 +243,35 @@ public:
     // what is returned by the Windows API. For example, it should
     // store VK_SHIFT instead of VK_RSHIFT. The location information
     // should be stored in |modifiers|.
-    int key;
+    int key = 0;
 
     // |charCode| is the text generated by this keystroke.  |unmodifiedCharCode|
     // is |charCode|, but unmodified by an concurrently-held modifiers (except
     // shift).  This is useful for working out shortcut keys.
-    WebUChar charCode;
-    WebUChar unmodifiedCharCode;
-
-    WebKeyboardEvent()
-        : WebInputEvent(sizeof(WebKeyboardEvent))
-        , key(0)
-        , charCode(0)
-        , unmodifiedCharCode(0)
-    {
-    }
+    WebUChar charCode = 0;
+    WebUChar unmodifiedCharCode = 0;
+
+    WebKeyboardEvent() : WebInputEvent(sizeof(WebKeyboardEvent)) {}
+};
+
+// WebWheelEvent --------------------------------------------------------------
+
+class WebWheelEvent : public WebInputEvent {
+public:
+    float x = 0;
+    float y = 0;
+    float offsetX = 0;
+    float offsetY = 0;
+
+    WebWheelEvent() : WebInputEvent(sizeof(WebWheelEvent)) {}
 };
 
-// WebGestureEvent --------------------------------------------------------------
+// WebGestureEvent ------------------------------------------------------------
 
 class WebGestureEvent : public WebInputEvent {
 public:
-    int x;
-    int y;
-    int globalX;
-    int globalY;
-    WebGestureDevice sourceDevice;
+    float x = 0;
+    float y = 0;
 
     union {
         // Tap information must be set for GestureTap, GestureTapUnconfirmed,
@@ -320,10 +328,6 @@ public:
 
     WebGestureEvent()
         : WebInputEvent(sizeof(WebGestureEvent))
-        , x(0)
-        , y(0)
-        , globalX(0)
-        , globalY(0)
     {
         memset(&data, 0, sizeof(data));
     }