Added separator to sidebar ctx menu between show sidebar and position

fix brave/brave-browser#27880

New separator type(BOTH_SIDE_PADDED_SEPARATOR) is introduced to have
padding on both side.

browser/ui/views/sidebar/sidebar_control_view.cc

@@ -160,6 +160,8 @@ void SidebarControlView::ShowContextMenuForViewImpl(
       static_cast<int>(ShowSidebarOption::kShowNever),
       brave_l10n::GetLocalizedResourceUTF16String(
           IDS_SIDEBAR_SHOW_OPTION_NEVER));
+  context_menu_model_->AddSeparator(
+      ui::MenuSeparatorType::BOTH_SIDE_PADDED_SEPARATOR);
   context_menu_model_->AddTitle(brave_l10n::GetLocalizedResourceUTF16String(
       IDS_SIDEBAR_MENU_MODEL_POSITION_OPTION_TITLE));
   context_menu_model_->AddItemWithStringId(

chromium_src/ui/base/models/menu_separator_types.h

@@ -0,0 +1,15 @@
+// Copyright (c) 2023 The Brave Authors. All rights reserved.
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this file,
+// You can obtain one at https://mozilla.org/MPL/2.0/.
+
+#ifndef BRAVE_CHROMIUM_SRC_UI_BASE_MODELS_MENU_SEPARATOR_TYPES_H_
+#define BRAVE_CHROMIUM_SRC_UI_BASE_MODELS_MENU_SEPARATOR_TYPES_H_
+
+#define PADDED_SEPARATOR BOTH_SIDE_PADDED_SEPARATOR, PADDED_SEPARATOR
+
+#include "src/ui/base/models/menu_separator_types.h"
+
+#undef PADDED_SEPARATOR
+
+#endif  // BRAVE_CHROMIUM_SRC_UI_BASE_MODELS_MENU_SEPARATOR_TYPES_H_

chromium_src/ui/views/controls/menu/menu_separator.cc

@@ -0,0 +1,12 @@
+// Copyright (c) 2023 The Brave Authors. All rights reserved.
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this file,
+// You can obtain one at https://mozilla.org/MPL/2.0/.
+
+#define BRAVE_MENU_SEPARATOR_ON_PAINT               \
+  else if (type_ == ui::BOTH_SIDE_PADDED_SEPARATOR) \
+      paint_rect.Inset(gfx::Insets::VH(0, 8));
+
+#include "src/ui/views/controls/menu/menu_separator.cc"
+
+#undef BRAVE_MENU_SEPARATOR_ON_PAINT

patches/ui-views-controls-menu-menu_separator.cc.patch

@@ -0,0 +1,12 @@
+diff --git a/ui/views/controls/menu/menu_separator.cc b/ui/views/controls/menu/menu_separator.cc
+index be7ca4059bc2d7f78419dbf863fdb7c74070e9dc..6391ae9d86b0d66cca37d98f71506c2733b12edd 100644
+--- a/ui/views/controls/menu/menu_separator.cc
++++ b/ui/views/controls/menu/menu_separator.cc
+@@ -43,6 +43,7 @@ void MenuSeparator::OnPaint(gfx::Canvas* canvas) {
+   if (type_ == ui::PADDED_SEPARATOR)
+     paint_rect.Inset(
+         gfx::Insets::TLBR(0, menu_config.padded_separator_left_margin, 0, 0));
++  BRAVE_MENU_SEPARATOR_ON_PAINT
+   else if (menu_config.use_outer_border)
+     paint_rect.Inset(gfx::Insets::VH(0, 1));
+