Remove DeleteTask and convert remaining users.

chrome/browser/safe_browsing/download_protection_service.cc

Index: chrome/browser/safe_browsing/download_protection_service.cc
diff --git a/chrome/browser/safe_browsing/download_protection_service.cc b/chrome/browser/safe_browsing/download_protection_service.cc
index 26d36f08ee0b2ae52b7165f7516204a305293d10..533fc442b839e8d8669561a1148e03424f12dbb4 100644
--- a/chrome/browser/safe_browsing/download_protection_service.cc
+++ b/chrome/browser/safe_browsing/download_protection_service.cc
@@ -9,6 +9,7 @@
 #include "base/format_macros.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
+#include "base/message_loop_helpers.h"
 #include "base/metrics/histogram.h"
 #include "base/stl_util.h"
 #include "base/string_number_conversions.h"
@@ -456,7 +457,7 @@ class DownloadProtectionService::CheckClientDownloadRequest
 
  private:
   friend struct BrowserThread::DeleteOnThread<BrowserThread::UI>;
-  friend class DeleteTask<CheckClientDownloadRequest>;
+  friend class base::DeleteHelper<CheckClientDownloadRequest>;
 
   virtual ~CheckClientDownloadRequest() {
     DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));