Basic tests for DownloadUrl/DownloadUrlToFile.

content/browser/download/download_manager.cc

Index: content/browser/download/download_manager.cc
diff --git a/content/browser/download/download_manager.cc b/content/browser/download/download_manager.cc
index e56a92791a4d8e498195d9e8569d3c447b3ac1da..3470dc13f16022deb73df5a41247f4fd40e32a33 100644
--- a/content/browser/download/download_manager.cc
+++ b/content/browser/download/download_manager.cc
@@ -174,7 +174,7 @@ void DownloadManager::GetTemporaryDownloads(
   for (DownloadMap::iterator it = history_downloads_.begin();
        it != history_downloads_.end(); ++it) {
     if (it->second->is_temporary() &&
-        it->second->full_path().DirName() == dir_path)
+        (dir_path.empty() || it->second->full_path().DirName() == dir_path))
       result->push_back(it->second);
   }
 }
@@ -344,6 +344,7 @@ void DownloadManager::ContinueDownloadWithPath(DownloadItem* download,
   DCHECK(ContainsKey(active_downloads_, download_id));
 
   // Make sure the initial file name is set only once.
+  DCHECK(download->full_path().empty());
   download->OnPathDetermined(chosen_file);
 
   VLOG(20) << __FUNCTION__ << "()"