Add support for ordinal scroll amounts

ui/base/events/event.h

Index: ui/base/events/event.h
diff --git a/ui/base/events/event.h b/ui/base/events/event.h
index b691118c064954ffd7b74149ad0541340fdaec1a..91a1ac897d28bb7b315a2eb7fe62c80d9de8b9fa 100644
--- a/ui/base/events/event.h
+++ b/ui/base/events/event.h
@@ -622,6 +622,8 @@ class UI_EXPORT ScrollEvent : public MouseEvent {
       : MouseEvent(model, source, target),
         x_offset_(model.x_offset_),
         y_offset_(model.y_offset_),
+        x_offset_ordinal_(model.x_offset_ordinal_),
+        y_offset_ordinal_(model.y_offset_ordinal_),
         finger_count_(model.finger_count_){
   }
 
@@ -632,6 +634,8 @@ class UI_EXPORT ScrollEvent : public MouseEvent {
               int flags,
               float x_offset,
               float y_offset,
+              float x_offset_ordinal,
+              float y_offset_ordinal,
               int finger_count);
 
   // Scale the scroll event's offset value.
@@ -641,11 +645,18 @@ class UI_EXPORT ScrollEvent : public MouseEvent {
 
   float x_offset() const { return x_offset_; }
   float y_offset() const { return y_offset_; }
+  float x_offset_ordinal() const { return x_offset_ordinal_; }
+  float y_offset_ordinal() const { return y_offset_ordinal_; }
   int finger_count() const { return finger_count_; }
 
  private:
+  // Potential accelerated offsets.
   float x_offset_;
   float y_offset_;
+  // Unaccelerated offsets.
+  float x_offset_ordinal_;
+  float y_offset_ordinal_;
+  // Number of fingers on the pad.
   int finger_count_;
 };