Downloads: Added transient flag to download item and download database

chrome/browser/ntp_snippets/fake_download_item.h

 // Copyright 2016 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.
 
 #ifndef CHROME_BROWSER_NTP_SNIPPETS_FAKE_DOWNLOAD_ITEM_H_
 #define CHROME_BROWSER_NTP_SNIPPETS_FAKE_DOWNLOAD_ITEM_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 98 matching lines @@
   int64_t GetReceivedBytes() const override;
   const std::vector<DownloadItem::ReceivedSlice>& GetReceivedSlices()
       const override;
   bool CanShowInFolder() override;
   bool CanOpenDownload() override;
   bool ShouldOpenFileBasedOnExtension() override;
   bool GetOpenWhenComplete() const override;
   bool GetAutoOpened() override;
   bool GetOpened() const override;
   base::Time GetLastAccessTime() const override;
+  bool IsVisible() const override;
   content::BrowserContext* GetBrowserContext() const override;
   content::WebContents* GetWebContents() const override;
   void OnContentCheckCompleted(
       content::DownloadDangerType danger_type) override;
   void SetOpenWhenComplete(bool open) override;
   void SetOpened(bool opened) override;
   void SetLastAccessTime(const base::Time& time) override;
   void SetDisplayName(const base::FilePath& name) override;
   std::string DebugString(bool verbose) const override;
 
@@ skipping 14 matching lines @@
   std::vector<GURL> dummy_url_vector;
   GURL dummy_url;
   base::FilePath dummy_file_path;
 
   DISALLOW_COPY_AND_ASSIGN(FakeDownloadItem);
 };
 
 }  // namespace test
 
 #endif  // CHROME_BROWSER_NTP_SNIPPETS_FAKE_DOWNLOAD_ITEM_H_