Fixed issue with DownloadTestObserver.

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 "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/file_path.h"
 #include "base/file_util.h"
 #include "base/memory/ref_counted.h"
 #include "base/path_service.h"
@@ skipping 701 matching lines @@
 
       DownloadManagerForBrowser(browser())->DownloadUrl(
           url, GURL(""), "", false, -1, save_info, web_contents);
     } else {
       // Navigate to URL normally, wait until done.
       ui_test_utils::NavigateToURLBlockUntilNavigationsComplete(browser(),
                                                                 url,
                                                                 1);
     }
 
-    if (download_info.show_download_item)
+    if (download_info.show_download_item) {
       observer->WaitForFinished();
+      DCHECK_EQ(0u, observer->NumOtherDownloadsSeen());
+    }
 
     // Validate that the correct file was downloaded.
     download_items.clear();
     GetDownloads(browser(), &download_items);
     size_t item_count = download_info.show_download_item ? 1 : 0;
     ASSERT_EQ(item_count, download_items.size());
 
     if (download_info.show_download_item) {
       DownloadItem* item = download_items[0];
       ASSERT_EQ(url, item->GetOriginalUrl());
@@ skipping 1340 matching lines @@
     "zip_file_not_found.zip",
     DOWNLOAD_NAVIGATE,
     DOWNLOAD_INTERRUPT_REASON_SERVER_FAILED,
     false
   };
 
   // Do initial setup.
   ASSERT_TRUE(InitialSetup(false));
   DownloadFileCheckErrors(download_info);
 }