[Cleanup] Remove mac code from aura/ash/views

ui/aura/root_window_mac.mm

-// Copyright (c) 2012 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#import "ui/aura/root_window_mac.h"
-
-#include "ui/aura/root_window_host_mac.h"
-
-@implementation RootWindowMac
-
-- (id)initWithContentRect:(NSRect)contentRect
-                styleMask:(NSUInteger)windowStyle
-                  backing:(NSBackingStoreType)bufferingType
-                    defer:(BOOL)deferCreation {
-  if ((self = [super initWithContentRect:contentRect
-                               styleMask:windowStyle
-                                 backing:bufferingType
-                                   defer:deferCreation])) {
-    hostDelegate_ = NULL;
-  }
-  return self;
-}
-
-- (void)setHostDelegate:(aura::RootWindowHostMacDelegate*)hostDelegate {
-  hostDelegate_ = hostDelegate;
-}
-
-- (void)sendEvent:(NSEvent*)event {
-  // Allow both the Cocoa machinery and the Aura machinery to handle the event.
-  [super sendEvent:event];
-  if (hostDelegate_)
-    hostDelegate_->SendEvent(event);
-}
-
-@end