Define a single macro for enabling backup function.

chrome/browser/sync/backup_rollback_controller.cc

 // Copyright 2014 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/sync/backup_rollback_controller.h"
 
 #include "base/command_line.h"
 #include "base/message_loop/message_loop.h"
 #include "chrome/browser/sync/managed_user_signin_manager_wrapper.h"
 #include "chrome/common/chrome_switches.h"
 #include "components/sync_driver/sync_prefs.h"
 
 namespace browser_sync {
 
-#if defined(OS_WIN) || defined(OS_MACOSX) || (defined(OS_LINUX) && !defined(OS_CHROMEOS))
+#if defined(ENABLE_PRE_SYNC_BACKUP)
 // Number of rollback attempts to try before giving up.
 static const int kRollbackLimits = 3;
 #endif
 
 BackupRollbackController::BackupRollbackController(
     sync_driver::SyncPrefs* sync_prefs,
     const ManagedUserSigninManagerWrapper* signin,
     base::Closure start_backup,
     base::Closure start_rollback)
     : sync_prefs_(sync_prefs),
       signin_(signin),
       start_backup_(start_backup),
       start_rollback_(start_rollback),
       weak_ptr_factory_(this) {
 }
 
 BackupRollbackController::~BackupRollbackController() {
 }
 
 void BackupRollbackController::Start(base::TimeDelta delay) {
-#if defined(OS_WIN) || defined(OS_MACOSX) || (defined(OS_LINUX) && !defined(OS_CHROMEOS))
+#if defined(ENABLE_PRE_SYNC_BACKUP)
   if (CommandLine::ForCurrentProcess()->HasSwitch(
           switches::kSyncDisableBackup)) {
     return;
   }
 
   if (!CommandLine::ForCurrentProcess()->HasSwitch(
           switches::kSyncEnableRollback)) {
     sync_prefs_->SetRemainingRollbackTries(0);
   }
 
   if (delay == base::TimeDelta()) {
     TryStart();
   } else {
     base::MessageLoop::current()->PostDelayedTask(
         FROM_HERE,
         base::Bind(&BackupRollbackController::TryStart,
                    weak_ptr_factory_.GetWeakPtr()),
         delay);
   }
 #endif
 }
 
 void BackupRollbackController::OnRollbackReceived() {
-#if defined(OS_WIN) || defined(OS_MACOSX) || (defined(OS_LINUX) && !defined(OS_CHROMEOS))
+#if defined(ENABLE_PRE_SYNC_BACKUP)
   sync_prefs_->SetRemainingRollbackTries(kRollbackLimits);
 #endif
 }
 
 void BackupRollbackController::OnRollbackDone() {
-#if defined(OS_WIN) || defined(OS_MACOSX) || (defined(OS_LINUX) && !defined(OS_CHROMEOS))
+#if defined(ENABLE_PRE_SYNC_BACKUP)
   sync_prefs_->SetRemainingRollbackTries(0);
 #endif
 }
 
 void BackupRollbackController::TryStart() {
   if (!signin_->GetEffectiveUsername().empty()) {
     DVLOG(1) << "Don't start backup/rollback when user is signed in.";
     return;
   }
 
   int rollback_tries = sync_prefs_->GetRemainingRollbackTries();
   if (rollback_tries > 0) {
     DVLOG(1) << "Start rollback.";
     sync_prefs_->SetRemainingRollbackTries(rollback_tries - 1);
     start_rollback_.Run();
   } else {
     DVLOG(1) << "Start backup.";
     start_backup_.Run();
   }
 }
 
 }  // namespace browser_sync