Guard Ash code with USE_ASH in chrome/browser/lifetime/

chrome/browser/lifetime/application_lifetime_aura.cc

 // 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.
 
 #include "chrome/browser/lifetime/application_lifetime.h"
 
-#include "ash/shell.h"
 #include "base/command_line.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/notifications/notification_ui_manager.h"
 #include "chrome/common/chrome_switches.h"
 #include "ui/aura/client/capture_client.h"
 #include "ui/aura/window_event_dispatcher.h"
 #include "ui/views/widget/widget.h"
 
+#if defined(USE_ASH)
+#include "ash/shell.h"
+#endif
+
 namespace chrome {
 
 void HandleAppExitingForPlatform() {
   // Close all non browser windows now. Those includes notifications
   // and windows created by Ash (launcher, background, etc).
   g_browser_process->notification_ui_manager()->CancelAll();
 
+#if defined(USE_ASH)
   // This may be called before |ash::Shell| is initialized when
   // XIOError is reported.  crbug.com/150633.
   if (ash::Shell::HasInstance()) {
     // Releasing the capture will close any menus that might be open:
     // http://crbug.com/134472
     aura::client::GetCaptureClient(ash::Shell::GetPrimaryRootWindow())->
         SetCapture(NULL);
   }
+#endif  // defined(USE_ASH)
 
   views::Widget::CloseAllSecondaryWidgets();
 
 #if defined(OS_CHROMEOS)
   if (!base::CommandLine::ForCurrentProcess()->HasSwitch(
           switches::kDisableZeroBrowsersOpenForTests)) {
     // App is exiting, call DecrementKeepAliveCount() on behalf of Aura Shell.
     DecrementKeepAliveCount();
     // Make sure we have notified the session manager that we are exiting.
     // This might be called from FastShutdown() or CloseAllBrowsers(), but not
     // if something prevents a browser from closing before SetTryingToQuit()
     // gets called (e.g. browser->TabsNeedBeforeUnloadFired() is true).
     // NotifyAndTerminate does nothing if called more than once.
     NotifyAndTerminate(true);
   }
-#endif  // OS_CHROMEOS
+#endif  // defined(OS_CHROMEOS)

[sky, 2015/11/20 23:46:40]

IMO this style of comments are a waste.

[mohsen, 2015/11/21 01:05:17]

Do you mean the whole comment or just the part I added? If the former, that
definitely makes sense in cases like here where the block is small.

[sky, 2015/11/22 16:00:22]

I mean the trailing // defined(OS_CHROMEOS). Comments like that are useful for
ifdefs spanning a large number of lines, or when there are lots of nested
ifdefs, but that isn't the case here. The style guide doesn't comment one way or
the other on this, so I leave the decision to you.

 }
 
 }  // namespace chrome