[Downloads] Rework how hashes are calculated for download files.

chrome/browser/extensions/api/downloads/downloads_api_browsertest.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.
 
 // Disable everything on windows only. http://crbug.com/306144
 #ifndef OS_WIN
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 423 matching lines @@
           url_chain,
           GURL(),  // URL Chain, referrer
           std::string(),
           std::string(),  // mime_type, original_mime_type
           current,
           current,  // start_time, end_time
           std::string(),
           std::string(),  // etag, last_modified
           1,
           1,                      // received_bytes, total_bytes
+          std::string(),          // hash
           history_info[i].state,  // state
           history_info[i].danger_type,
           (history_info[i].state != content::DownloadItem::CANCELLED
                ? content::DOWNLOAD_INTERRUPT_REASON_NONE
                : content::DOWNLOAD_INTERRUPT_REASON_USER_CANCELED),
           false);  // opened
       items->push_back(item);
     }
 
     // Order by ID so that they are in the order that we created them.
@@ skipping 3730 matching lines @@
   EXPECT_EQ(downloads::FILENAME_CONFLICT_ACTION_PROMPT, conflict_action);
   EXPECT_FALSE(warnings.empty());
   EXPECT_EQ(Warning::kDownloadFilenameConflict,
             warnings.begin()->warning_type());
   EXPECT_EQ("incumbent", warnings.begin()->extension_id());
 }
 
 }  // namespace extensions
 
 #endif  // http://crbug.com/306144