Split the event library into a cross-platform and native part. Part 1.

ui/events/cocoa/events_mac.mm

Index: ui/events/cocoa/events_mac.mm
diff --git a/ui/events/cocoa/events_mac.mm b/ui/events/cocoa/events_mac.mm
index 4772b2728333c9908cfcad11076ff002a1649755..373d47fa8eeb3e68ddf2af15d51c855b5c857ef1 100644
--- a/ui/events/cocoa/events_mac.mm
+++ b/ui/events/cocoa/events_mac.mm
@@ -152,14 +152,6 @@ gfx::Vector2d GetMouseWheelOffset(const base::NativeEvent& event) {
   }
 }
 
-base::NativeEvent CopyNativeEvent(const base::NativeEvent& event) {
-  return [event copy];
-}
-
-void ReleaseCopiedNativeEvent(const base::NativeEvent& event) {
-  [event release];
-}
-
 void IncrementTouchIdRefCount(const base::NativeEvent& native_event) {
   NOTIMPLEMENTED();
 }