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

chrome/browser/download/download_browsertest.cc

Index: chrome/browser/download/download_browsertest.cc
diff --git a/chrome/browser/download/download_browsertest.cc b/chrome/browser/download/download_browsertest.cc
index 331fb0e600faee41c2a49711bb6055fbf19927d7..7c933fb50f9540bb128359458f5d073aaefc019f 100644
--- a/chrome/browser/download/download_browsertest.cc
+++ b/chrome/browser/download/download_browsertest.cc
@@ -1718,10 +1718,10 @@ IN_PROC_BROWSER_TEST_F(DownloadTest, DownloadHistoryCheck) {
   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

[svaldez, 2016/03/09 19:27:33]

Is this just an incidental change?

[asanka, 2016/03/10 16:48:08]

This is a result of the explicit split between the two interrupt modes:
InterruptAndDiscardPartialState() vs. InterruptWithPartialState().

Previously when a download was interrupted with a non-continuable error, the
intermediate file would be discarded but the metadata in DownloadItem wouldn't
be reset. This results in a descrepancy between the on-disk state and the
in-history state. Now DownloadItem resets the partial state data along with the
partial file when it is interrupted with a non-continuable error.

Interrupt() was split into the two modes precisely because we want to keep the
partial state meta-data in-sync with the on-disk state.

+                                      // 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(