Enable rollback by default on trunk (m38).

chrome/browser/sync/profile_sync_service_unittest.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 "base/basictypes.h"
 #include "base/command_line.h"
 #include "base/compiler_specific.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/run_loop.h"
 #include "base/strings/string_number_conversions.h"
@@ skipping 525 matching lines @@
 
   // First sync time is erased once backup starts.
   EXPECT_TRUE(sync_prefs.GetFirstSyncTime().is_null());
 
   EXPECT_EQ(2u, delete_dir_param.size());
   EXPECT_FALSE(delete_dir_param[0]);
   EXPECT_TRUE(delete_dir_param[1]);
 }
 
 TEST_F(ProfileSyncServiceTest, RollbackThenBackup) {
-  CommandLine::ForCurrentProcess()->AppendSwitch(
-      switches::kSyncEnableRollback);
-
   CreateService(browser_sync::MANUAL_START);
   service()->SetSyncSetupCompleted();
   ExpectDataTypeManagerCreation(3);
   std::vector<bool> delete_dir_param;
   ExpectSyncBackendHostCreationCollectDeleteDir(3, &delete_dir_param);
   IssueTestTokens();
   Initialize();
   EXPECT_TRUE(service()->sync_initialized());
   EXPECT_EQ(ProfileSyncService::SYNC, service()->backend_mode());
 
@@ skipping 56 matching lines @@
   // See that we can override the URL with a flag.
   CommandLine command_line(
       base::FilePath(base::FilePath(FILE_PATH_LITERAL("chrome.exe"))));
   command_line.AppendSwitchASCII(switches::kSyncServiceURL, "https://foo/bar");
   EXPECT_EQ("https://foo/bar",
             ProfileSyncService::GetSyncServiceURL(command_line).spec());
 }
 
 }  // namespace
 }  // namespace browser_sync