Downloads: Added transient flag to download item and download database

content/browser/download/download_item_impl.h

Index: content/browser/download/download_item_impl.h
diff --git a/content/browser/download/download_item_impl.h b/content/browser/download/download_item_impl.h
index 86f9f43220a94c243d22459f02d7ab7e20e46f99..2c824aaa120803aac2d134d2b05685d241d67ee8 100644
--- a/content/browser/download/download_item_impl.h
+++ b/content/browser/download/download_item_impl.h
@@ -77,6 +77,7 @@ class CONTENT_EXPORT DownloadItemImpl
       DownloadInterruptReason interrupt_reason,
       bool opened,
       base::Time last_access_time,
+      bool visible,
       const std::vector<DownloadItem::ReceivedSlice>& received_slices,
       const net::NetLogWithSource& net_log);
 
@@ -165,6 +166,7 @@ class CONTENT_EXPORT DownloadItemImpl
   bool GetAutoOpened() override;
   bool GetOpened() const override;
   base::Time GetLastAccessTime() const override;
+  bool IsVisible() const override;
   BrowserContext* GetBrowserContext() const override;
   WebContents* GetWebContents() const override;
   void OnContentCheckCompleted(DownloadDangerType danger_type) override;
@@ -629,6 +631,9 @@ class CONTENT_EXPORT DownloadItemImpl
   // Time when the download was last accessed.
   base::Time last_access_time_;
 
+  // Whether the download item should be visible.
+  bool visible_ = true;
+
   // Did the delegate delay calling Complete on this download?
   bool delegate_delayed_complete_ = false;