refactor: rename the atom directory to shell

shell/browser/ui/cocoa/atom_native_widget_mac.mm

@@ -0,0 +1,27 @@
+// Copyright (c) 2018 GitHub, Inc.
+// Use of this source code is governed by the MIT license that can be
+// found in the LICENSE file.
+
+#include "atom/browser/ui/cocoa/atom_native_widget_mac.h"
+
+#include "atom/browser/ui/cocoa/atom_ns_window.h"
+
+namespace atom {
+
+AtomNativeWidgetMac::AtomNativeWidgetMac(
+    NativeWindowMac* shell,
+    NSUInteger style_mask,
+    views::internal::NativeWidgetDelegate* delegate)
+    : views::NativeWidgetMac(delegate),
+      shell_(shell),
+      style_mask_(style_mask) {}
+
+AtomNativeWidgetMac::~AtomNativeWidgetMac() {}
+
+NativeWidgetMacNSWindow* AtomNativeWidgetMac::CreateNSWindow(
+    const remote_cocoa::mojom::CreateWindowParams* params) {
+  return [[[AtomNSWindow alloc] initWithShell:shell_
+                                    styleMask:style_mask_] autorelease];
+}
+
+}  // namespace atom