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

chrome/browser/download/chrome_download_manager_delegate.cc

 // Copyright (c) 2011 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 "chrome/browser/download/chrome_download_manager_delegate.h"
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/callback.h"
 #include "base/file_util.h"
@@ skipping 387 matching lines @@
         state.prompt_user_for_save_location = true;
     }
     if (download_prefs_->IsDownloadPathManaged()) {
       state.prompt_user_for_save_location = false;
     }
 
     // Determine the proper path for a download, by either one of the following:
     // 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();
     }
     state.suggested_path = state.suggested_path.Append(generated_name);
   } else {
     state.suggested_path = state.force_file_name;
   }
 
   if (!state.prompt_user_for_save_location && state.force_file_name.empty()) {
     state.is_dangerous_file =
@@ skipping 152 matching lines @@
     int32 download_id, int64 db_handle) {
   // It's not immediately obvious, but HistoryBackend::CreateDownload() can
   // call this function with an invalid |db_handle|. For instance, this can
   // happen when the history database is offline. We cannot have multiple
   // DownloadItems with the same invalid db_handle, so we need to assign a
   // unique |db_handle| here.
   if (db_handle == DownloadItem::kUninitializedHandle)
     db_handle = download_history_->GetNextFakeDbHandle();
   download_manager_->OnItemAddedToPersistentStore(download_id, db_handle);
 }