MacViews: Implement basic NSEvent -> ui::Event conversion for Mac

ui/events/events_stub.cc

Index: ui/events/events_stub.cc
diff --git a/ui/events/events_stub.cc b/ui/events/events_stub.cc
index bece37acbc94fdc815e97117f29f7f3a35adc685..bcd50fc6df2b1eed8cc37940d3001dba56abaee7 100644
--- a/ui/events/events_stub.cc
+++ b/ui/events/events_stub.cc
@@ -62,6 +62,15 @@ gfx::Vector2d GetMouseWheelOffset(const base::NativeEvent& native_event) {
   return gfx::Vector2d();
 }
 
+base::NativeEvent CopyNativeEvent(const base::NativeEvent& event) {
+  NOTIMPLEMENTED() <<
+      "Don't know how to copy base::NativeEvent for this platform";
+  return NULL;
+}
+
+void ReleaseCopiedNativeEvent(const base::NativeEvent& event) {
+}
+
 void ClearTouchIdIfReleased(const base::NativeEvent& native_event) {
   NOTIMPLEMENTED();
 }