Downloads: replace BrowserThread::FILE with task scheduler.

chrome/browser/download/download_prefs.cc

Index: chrome/browser/download/download_prefs.cc
diff --git a/chrome/browser/download/download_prefs.cc b/chrome/browser/download/download_prefs.cc
index eb39af5963a5d1d72a0f57540c3c8ce72971bfca..7a81ac538b50d0b660891239c5e9d11b2479d1c7 100644
--- a/chrome/browser/download/download_prefs.cc
+++ b/chrome/browser/download/download_prefs.cc
@@ -130,10 +130,9 @@ DownloadPrefs::DownloadPrefs(Profile* profile) : profile_(profile) {
   }
 
   // Ensure that the default download directory exists.
-  BrowserThread::PostTask(
-      BrowserThread::FILE, FROM_HERE,
-      base::BindOnce(base::IgnoreResult(&base::CreateDirectory),
-                     GetDefaultDownloadDirectoryForProfile()));
+  content::DownloadManager::GetTaskRunner()->PostTask(
+      FROM_HERE, base::BindOnce(base::IgnoreResult(&base::CreateDirectory),
+                                GetDefaultDownloadDirectoryForProfile()));
 #endif  // defined(OS_CHROMEOS)
 
 #if defined(OS_WIN) || defined(OS_LINUX) || defined(OS_MACOSX)