Use a DownloadRequestHandle pointer in construction to allow mocking for tests.

content/browser/download/download_file_unittest.cc

 // Copyright (c) 2011 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/file_util.h"
 #include "base/message_loop.h"
 #include "base/string_number_conversions.h"
 #include "content/browser/browser_thread_impl.h"
 #include "content/browser/download/download_create_info.h"
 #include "content/browser/download/download_file.h"
@@ skipping 53 matching lines @@
     download_manager_ = NULL;
     ui_thread_.message_loop()->RunAllPending();
   }
 
   virtual void CreateDownloadFile(scoped_ptr<DownloadFile>* file, int offset) {
     DownloadCreateInfo info;
     info.download_id = DownloadId(kValidIdDomain, kDummyDownloadId + offset);
     // info.request_handle default constructed to null.
     info.save_info.file_stream = file_stream_;
     file->reset(
-        new DownloadFile(&info, DownloadRequestHandle(), download_manager_));
+        new DownloadFile(&info, new DownloadRequestHandle(),
+                         download_manager_));
   }
 
   virtual void DestroyDownloadFile(scoped_ptr<DownloadFile>* file, int offset) {
     EXPECT_EQ(kDummyDownloadId + offset, (*file)->id());
     EXPECT_EQ(download_manager_, (*file)->GetDownloadManager());
     EXPECT_FALSE((*file)->in_progress());
     EXPECT_EQ(static_cast<int64>(expected_data_.size()),
               (*file)->bytes_so_far());
 
     // Make sure the data has been properly written to disk.
@@ skipping 108 matching lines @@
   // Check the files.
   EXPECT_FALSE(file_util::PathExists(path_3));
   EXPECT_TRUE(file_util::PathExists(path_4));
 
   // Check the hash.
   EXPECT_TRUE(download_file_->GetSha256Hash(&hash));
   EXPECT_EQ(kDataHash, base::HexEncode(hash.data(), hash.size()));
 
   DestroyDownloadFile(&download_file_, 0);
 }