Basic tests for DownloadUrl/DownloadUrlToFile.

content/browser/download/download_manager_impl.cc

Index: content/browser/download/download_manager_impl.cc
diff --git a/content/browser/download/download_manager_impl.cc b/content/browser/download/download_manager_impl.cc
index 1168a2990762e13457c03ce18654a70521545887..6045f1dc236f1a0ffedef3370b1a4b9b681ec850 100644
--- a/content/browser/download/download_manager_impl.cc
+++ b/content/browser/download/download_manager_impl.cc
@@ -183,7 +183,7 @@ void DownloadManagerImpl::GetTemporaryDownloads(
   for (DownloadMap::iterator it = history_downloads_.begin();
        it != history_downloads_.end(); ++it) {
     if (it->second->IsTemporary() &&
-        it->second->GetFullPath().DirName() == dir_path)
+        (dir_path.empty() || it->second->GetFullPath().DirName() == dir_path))
       result->push_back(it->second);
   }
 }
@@ -383,6 +383,7 @@ void DownloadManagerImpl::ContinueDownloadWithPath(
   DCHECK(ContainsKey(active_downloads_, download_id));
 
   // Make sure the initial file name is set only once.
+  DCHECK(download->GetFullPath().empty());
   download->OnPathDetermined(chosen_file);
 
   VLOG(20) << __FUNCTION__ << "()"