cros: Remove some OS platform ifdefs from ash

ash/mus/shell_delegate_mus.cc

 // Copyright 2016 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.
 
 #include "ash/mus/shell_delegate_mus.h"
 
 #include <utility>
 
 #include "ash/common/gpu_support_stub.h"
 #include "ash/common/palette_delegate.h"
 #include "ash/common/session/session_state_delegate.h"
 #include "ash/common/wm_shell.h"
 #include "ash/mus/accessibility_delegate_mus.h"
 #include "ash/mus/context_menu_mus.h"
 #include "ash/mus/shelf_delegate_mus.h"
+#include "ash/mus/system_tray_delegate_mus.h"
 #include "ash/mus/wallpaper_delegate_mus.h"
 #include "base/memory/ptr_util.h"
 #include "base/strings/string16.h"
 #include "base/strings/string_util.h"
 #include "components/user_manager/user_info_impl.h"
 #include "ui/gfx/image/image.h"
 
-#if defined(OS_CHROMEOS)
-#include "ash/mus/system_tray_delegate_mus.h"
-#else
-#include "ash/common/system/tray/default_system_tray_delegate.h"
-#endif
-
 namespace ash {
 namespace {
 
 class SessionStateDelegateStub : public SessionStateDelegate {
  public:
   SessionStateDelegateStub()
       : screen_locked_(false), user_info_(new user_manager::UserInfoImpl()) {}
 
   ~SessionStateDelegateStub() override {}
 
@@ skipping 105 matching lines @@
 
 void ShellDelegateMus::OpenUrlFromArc(const GURL& url) {
   NOTIMPLEMENTED();
 }
 
 ShelfDelegate* ShellDelegateMus::CreateShelfDelegate(ShelfModel* model) {
   return new ShelfDelegateMus();
 }
 
 SystemTrayDelegate* ShellDelegateMus::CreateSystemTrayDelegate() {
-#if defined(OS_CHROMEOS)
   return new SystemTrayDelegateMus();
-#else
-  // Windows and Linux do not support the services required for most system tray
-  // items. Use the same stub delegate as ash_shell_with_content.
-  return new DefaultSystemTrayDelegate();
-#endif
 }
 
 std::unique_ptr<WallpaperDelegate> ShellDelegateMus::CreateWallpaperDelegate() {
   return base::MakeUnique<WallpaperDelegateMus>();
 }
 
 SessionStateDelegate* ShellDelegateMus::CreateSessionStateDelegate() {
   // TODO: http://crbug.com/647416.
   NOTIMPLEMENTED() << " Using a stub SessionStateDeleagte implementation";
   return new SessionStateDelegateStub;
@@ skipping 38 matching lines @@
 void ShellDelegateMus::SetTouchscreenEnabledInPrefs(bool enabled,
                                                     bool use_local_state) {
   NOTIMPLEMENTED();
 }
 
 void ShellDelegateMus::UpdateTouchscreenStatusFromPrefs() {
   NOTIMPLEMENTED();
 }
 
 }  // namespace ash