Revert "Move on-demand update checks from the FILE thread to the blocking pool."

chrome/browser/ui/webui/help/version_updater_win.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/ui/webui/help/version_updater_win.h"
 
 #include "base/memory/weak_ptr.h"
 #include "base/task_runner_util.h"
 #include "base/win/win_util.h"
 #include "base/win/windows_version.h"
@@ skipping 21 matching lines @@
 
   // On-demand updates for Chrome don't work in Vista RTM when UAC is turned
   // off. So, in this case, the version updater must not mention
   // on-demand updates. Silent updates (in the background) should still
   // work as before - enabling UAC or installing the latest service pack
   // for Vista is another option.
   if (!(base::win::GetVersion() == base::win::VERSION_VISTA &&
         (base::win::OSInfo::GetInstance()->service_pack().major == 0) &&
         !base::win::UserAccountControlIsEnabled())) {
     callback_.Run(CHECKING, 0, base::string16());
-    BeginUpdateCheckInBlockingPool(false /* !install_update_if_possible */);
+    BeginUpdateCheckOnFileThread(false /* !install_update_if_possible */);
   }
 }
 
 void VersionUpdaterWin::OnUpdateCheckComplete(
     const base::string16& new_version) {
   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
   Status status = CHECKING;
   if (new_version.empty()) {
     // Google Update says that no new version is available. Check to see if a
     // restart is needed for a previously-applied update to take effect.
     if (base::PostTaskAndReplyWithResult(
             content::BrowserThread::GetBlockingPool(),
             FROM_HERE,
             base::Bind(&upgrade_util::IsUpdatePendingRestart),
             base::Bind(&VersionUpdaterWin::OnPendingRestartCheck,
                        weak_factory_.GetWeakPtr()))) {
       // Early exit since callback_ will be Run in OnPendingRestartCheck.
       return;
     }
     // Failure to post the task means that Chrome is shutting down. A pending
     // update (if there is one) will be applied as Chrome exits, so tell the
     // caller that it is up to date in either case.
     status = UPDATED;
   } else {
     // Notify the caller that the update is now beginning and initiate it.
     status = UPDATING;
-    BeginUpdateCheckInBlockingPool(true /* install_update_if_possible */);
+    BeginUpdateCheckOnFileThread(true /* install_update_if_possible */);
   }
   callback_.Run(status, 0, base::string16());
 }
 
 void VersionUpdaterWin::OnUpgradeProgress(int progress,
                                           const base::string16& new_version) {
   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
   callback_.Run(UPDATING, progress, base::string16());
 }
 
@@ skipping 26 matching lines @@
         message = l10n_util::GetStringFUTF16Int(IDS_UPGRADE_ERROR, error_code);
       } else {
         message = l10n_util::GetStringFUTF16(
             IDS_ABOUT_BOX_ERROR_DURING_UPDATE_CHECK, html_error_message);
       }
       break;
   }
   callback_.Run(status, 0, message);
 }
 
-void VersionUpdaterWin::BeginUpdateCheckInBlockingPool(
+void VersionUpdaterWin::BeginUpdateCheckOnFileThread(
     bool install_update_if_possible) {
   // Disconnect from any previous attempts to avoid redundant callbacks.
   weak_factory_.InvalidateWeakPtrs();
-  base::SequencedWorkerPool* blocking_pool =
-      content::BrowserThread::GetBlockingPool();
-  BeginUpdateCheck(blocking_pool->GetSequencedTaskRunnerWithShutdownBehavior(
-                       blocking_pool->GetSequenceToken(),
-                       base::SequencedWorkerPool::CONTINUE_ON_SHUTDOWN),
+  BeginUpdateCheck(content::BrowserThread::GetTaskRunnerForThread(
+                       content::BrowserThread::FILE),
                    g_browser_process->GetApplicationLocale(),
                    install_update_if_possible, owner_widget_,
                    weak_factory_.GetWeakPtr());
 }
 
 void VersionUpdaterWin::OnPendingRestartCheck(bool is_update_pending_restart) {
   callback_.Run(is_update_pending_restart ? NEARLY_UPDATED : UPDATED, 0,
                 base::string16());
 }
 
 VersionUpdater* VersionUpdater::Create(content::WebContents* web_contents) {
   // Retrieve the HWND for the browser window that is hosting the update check.
   // This will be used as the parent for a UAC prompt, if needed. It's possible
   // this this window will no longer have focus by the time UAC is needed. In
   // that case, the UAC prompt will appear in the taskbar and will require a
   // user click. This is the least surprising thing we can do for the user, and
   // is the intended behavior for Windows applications.
   // It's also possible that the browser window hosting the update check will
   // have been closed by the time the UAC prompt is needed. In this case, the
   // web contents may no longer be hosted in a window, leading either
   // GetTopLevelNativeWindow or GetHost to return null. Passing nullptr to
   // VersionUpdaterWin will then also cause the UAC prompt to appear in the task
   // bar.
   gfx::NativeWindow window = web_contents->GetTopLevelNativeWindow();
   aura::WindowTreeHost* window_tree_host = window ? window->GetHost() : nullptr;
   return new VersionUpdaterWin(
       window_tree_host ? window_tree_host->GetAcceleratedWidget() : nullptr);
 }