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

chrome/browser/download/download_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.
 
 #include "chrome/browser/download/download_browsertest.h"
 
 #include <stdint.h>
 #include <sstream>
 #include <utility>
 
@@ skipping 1700 matching lines @@
   // job. The download isn't continuable, so there's no intermediate file.
   history::DownloadRow& row1(downloads_in_database->at(0));
   EXPECT_EQ(DestinationFile(browser(), file), row1.target_path);
   EXPECT_TRUE(row1.current_path.empty());
   ASSERT_EQ(2u, row1.url_chain.size());
   EXPECT_EQ(redirect_url.spec(), row1.url_chain[0].spec());
   EXPECT_EQ(download_url.spec(), row1.url_chain[1].spec());
   EXPECT_EQ(history::DownloadDangerType::NOT_DANGEROUS, row1.danger_type);
   EXPECT_LE(start, row1.start_time);
   EXPECT_GE(end, row1.end_time);
-  EXPECT_EQ(net::URLRequestSlowDownloadJob::kFirstDownloadSize,
-            row1.received_bytes);
-  EXPECT_EQ(net::URLRequestSlowDownloadJob::kFirstDownloadSize
-            + net::URLRequestSlowDownloadJob::kSecondDownloadSize,
+  EXPECT_EQ(0, row1.received_bytes);  // There's no ETag. So the intermediate
+                                      // state is discarded.
+  EXPECT_EQ(net::URLRequestSlowDownloadJob::kFirstDownloadSize +
+                net::URLRequestSlowDownloadJob::kSecondDownloadSize,
             row1.total_bytes);
   EXPECT_EQ(history::DownloadState::INTERRUPTED, row1.state);
   EXPECT_EQ(history::ToHistoryDownloadInterruptReason(
                 content::DOWNLOAD_INTERRUPT_REASON_NETWORK_FAILED),
             row1.interrupt_reason);
   EXPECT_FALSE(row1.opened);
 }
 
 // Make sure a dangerous file shows up properly in the history.
 IN_PROC_BROWSER_TEST_F(DownloadTest, DownloadHistoryDangerCheck) {
@@ skipping 1790 matching lines @@
 
   scoped_ptr<content::DownloadTestObserver> observer(DangerousDownloadWaiter(
       browser(), 1, content::DownloadTestObserver::ON_DANGEROUS_DOWNLOAD_DENY));
   ui_test_utils::NavigateToURL(browser(), extension_url);
 
   observer->WaitForFinished();
 
   // Download shelf should close.
   EXPECT_FALSE(browser()->window()->IsDownloadShelfVisible());
 }