ui: Remove some unnecessary functions from the API.

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 7675eb6af0589a3065a18da0e405766b17d5e678..74c28a23767fd23a54e3cfd224f23391647b9a25 100644
--- a/ui/events/cocoa/events_mac.mm
+++ b/ui/events/cocoa/events_mac.mm
@@ -204,20 +204,6 @@ bool GetGestureTimes(const base::NativeEvent& native_event,
   return false;
 }
 
-void SetNaturalScroll(bool enabled) {
-  NOTIMPLEMENTED();
-}
-
-bool IsNaturalScrollEnabled() {
-  NOTIMPLEMENTED();
-  return false;
-}
-
-bool IsTouchpadEvent(const base::NativeEvent& native_event) {
-  NOTIMPLEMENTED();
-  return false;
-}
-
 KeyboardCode KeyboardCodeFromNative(const base::NativeEvent& native_event) {
   return KeyboardCodeFromNSEvent(native_event);
 }