Created a DownloadManager interface, for use in unit tests..

chrome/browser/download/chrome_download_manager_delegate.cc

Index: chrome/browser/download/chrome_download_manager_delegate.cc
diff --git a/chrome/browser/download/chrome_download_manager_delegate.cc b/chrome/browser/download/chrome_download_manager_delegate.cc
index deaa40cab892041f377b671fbc8c3367e95846bc..a0335e21f59a45b469910d1fa25b65f54dc5eed7 100644
--- a/chrome/browser/download/chrome_download_manager_delegate.cc
+++ b/chrome/browser/download/chrome_download_manager_delegate.cc
@@ -386,8 +386,8 @@ void ChromeDownloadManagerDelegate::CheckVisitedReferrerBeforeDone(
     // 1) using the default download directory.
     // 2) prompting the user.
     if (state.prompt_user_for_save_location &&
-        !download_manager_->last_download_path().empty()) {
-      state.suggested_path = download_manager_->last_download_path();
+        !download_manager_->LastDownloadPath().empty()) {
+      state.suggested_path = download_manager_->LastDownloadPath();
     } else {
       state.suggested_path = download_prefs_->download_path();
     }