[Downloads] Do not store error responses during resumption.

content/browser/download/download_browsertest.cc

Index: content/browser/download/download_browsertest.cc
diff --git a/content/browser/download/download_browsertest.cc b/content/browser/download/download_browsertest.cc
index aaa6dbd3992831ffa52b325e3d1e2ddb00ddc437..18af2c4df788bb6fe316db01c8ab445beda154b4 100644
--- a/content/browser/download/download_browsertest.cc
+++ b/content/browser/download/download_browsertest.cc
@@ -1194,6 +1194,67 @@ IN_PROC_BROWSER_TEST_P(DownloadResumptionContentTest, RedirectBeforeResume) {
       download->GetTargetFilePath()));
 }
 
+// If a resumption request results in a redirect, the response should be ignored
+// and the download should be marked as interrupted again.
+IN_PROC_BROWSER_TEST_P(DownloadResumptionContentTest, RedirectWhileResume) {
+  TestDownloadRequestHandler request_handler(
+      GURL("http://example.com/first-url"));
+  TestDownloadRequestHandler::Parameters parameters =
+      TestDownloadRequestHandler::Parameters::WithSingleInterruption();
+  ++parameters.pattern_generator_seed;
+  request_handler.StartServing(parameters);
+
+  // We should never send a request to the decoy. If we do, the request will
+  // always succeed, which results in behavior that diverges from what we want,
+  // which is for the download to return to being interrupted.
+  TestDownloadRequestHandler decoy_request_handler(
+      GURL("http://example.com/decoy"));
+  decoy_request_handler.StartServing(TestDownloadRequestHandler::Parameters());
+
+  DownloadItem* download = StartDownloadAndReturnItem(
+      initiator_shell_for_resumption(), request_handler.url());
+  WaitForInterrupt(download);
+
+  // Upon resumption, the server starts responding with a redirect. This
+  // response should not be accepted.
+  request_handler.StartServingStaticResponse(
+      "HTTP/1.1 302 Redirect\r\n"
+      "Location: http://example.com/decoy\r\n"
+      "\r\n");
+  PrepareToResume();
+  download->Resume();
+  WaitForInterrupt(download);
+  EXPECT_EQ(DOWNLOAD_INTERRUPT_REASON_SERVER_UNREACHABLE,
+            download->GetLastReason());
+
+  // Back to the original request handler. Resumption should now succeed, and
+  // use the partial data it had prior to the first interruption.
+  request_handler.StartServing(parameters);
+  download->Resume();
+  WaitForCompletion(download);
+
+  ASSERT_EQ(parameters.size, download->GetReceivedBytes());
+  ASSERT_EQ(parameters.size, download->GetTotalBytes());
+  ASSERT_NO_FATAL_FAILURE(ReadAndVerifyFileContents(
+      parameters.pattern_generator_seed, parameters.size,
+      download->GetTargetFilePath()));
+
+  // Characterization risk: The next portion of the test examines the requests
+  // that were sent out while downloading our resource. These requests
+  // correspond to the requests that were generated by the browser and the
+  // downloads system and may change as implementation details change.
+  TestDownloadRequestHandler::CompletedRequests requests;
+  request_handler.GetCompletedRequestInfo(&requests);
+
+  ASSERT_EQ(3u, requests.size());
+
+  // None of the request should have transferred the entire resource. The
+  // redirect response shows up as a response with 0 bytes transferred.
+  EXPECT_GT(parameters.size, requests[0].transferred_byte_count);
+  EXPECT_EQ(0, requests[1].transferred_byte_count);
+  EXPECT_GT(parameters.size, requests[2].transferred_byte_count);
+}
+
 // If the server response for the resumption request specifies a bad range (i.e.
 // not the range that was requested or an invalid or missing Content-Range
 // header), then the download should be marked as interrupted again without