events: Make sure the unaccelerated scroll deltas get adjusted properly for device-scale-factor.

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 a50823a9e229ea49db69f7a94586334be52e6bde..95e34ce50978357be178c70aba235c71ccf6d74d 100644
--- a/ui/base/events/event.h
+++ b/ui/base/events/event.h
@@ -655,6 +655,10 @@ class UI_EXPORT ScrollEvent : public MouseEvent {
   float y_offset_ordinal() const { return y_offset_ordinal_; }
   int finger_count() const { return finger_count_; }
 
+  // Overridden from LocatedEvent.
+  virtual void UpdateForRootTransform(
+      const gfx::Transform& root_transform) OVERRIDE;
+
  private:
   // Potential accelerated offsets.
   float x_offset_;