Handle alternate types in HandleMouseEvent.

ui/base/events/event.cc

Index: ui/base/events/event.cc
diff --git a/ui/base/events/event.cc b/ui/base/events/event.cc
index 1ade95089d71155417d566f3842a6888a4e01ac9..e976e9a8910258af02ec67370807bb05ac7f59aa 100644
--- a/ui/base/events/event.cc
+++ b/ui/base/events/event.cc
@@ -419,6 +419,12 @@ MouseWheelEvent::MouseWheelEvent(const MouseEvent& mouse_event,
   DCHECK(type() == ET_MOUSEWHEEL);
 }
 
+MouseWheelEvent::MouseWheelEvent(const MouseWheelEvent& mouse_wheel_event)
+    : MouseEvent(mouse_wheel_event),
+      offset_(mouse_wheel_event.offset()) {
+  DCHECK(type() == ET_MOUSEWHEEL);
+}
+
 #if defined(OS_WIN)
 // This value matches windows WHEEL_DELTA.
 // static
@@ -428,6 +434,18 @@ const int MouseWheelEvent::kWheelDelta = 120;
 const int MouseWheelEvent::kWheelDelta = 53;
 #endif
 
+void MouseWheelEvent::UpdateForRootTransform(
+    const gfx::Transform& inverted_root_transform) {
+  LocatedEvent::UpdateForRootTransform(inverted_root_transform);
+  gfx::DecomposedTransform decomp;
+  bool success = gfx::DecomposeTransform(&decomp, inverted_root_transform);
+  DCHECK(success);
+  if (decomp.scale[0])
+    offset_.set_x(offset_.x() * decomp.scale[0]);
+  if (decomp.scale[1])
+    offset_.set_y(offset_.y() * decomp.scale[1]);
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 // TouchEvent