Bug 1259296 - Scroll snap in the compositor in response to wheel events. r=kats

MozReview-Commit-ID: 9fOlssstgvR

widget/InputData.h

@@ -6,8 +6,9 @@
 #ifndef InputData_h__
 #define InputData_h__
 
-#include "nsIDOMWheelEvent.h"
 #include "nsDebug.h"
+#include "nsIDOMWheelEvent.h"
+#include "nsIScrollableFrame.h"
 #include "nsPoint.h"
 #include "nsTArray.h"
 #include "Units.h"
@@ -577,6 +578,22 @@ public:
     return SCROLLDELTA_LINE;
   }
 
+  static nsIScrollableFrame::ScrollUnit
+  ScrollUnitForDeltaType(ScrollDeltaType aDeltaType)
+  {
+    switch (aDeltaType) {
+    case SCROLLDELTA_LINE:
+      return nsIScrollableFrame::LINES;
+    case SCROLLDELTA_PAGE:
+      return nsIScrollableFrame::PAGES;
+    case SCROLLDELTA_PIXEL:
+      return nsIScrollableFrame::DEVICE_PIXELS;
+    default:
+      MOZ_CRASH();
+    }
+    return nsIScrollableFrame::LINES;
+  }
+
   enum ScrollMode
   {
     SCROLLMODE_INSTANT,