Reland DownloadItem::Observer::OnDownloadDestroyed() replaces DownloadItem::REMOVING

content/public/browser/download_item.h

Index: content/public/browser/download_item.h
diff --git a/content/public/browser/download_item.h b/content/public/browser/download_item.h
index 84ca1602d356436a1dab627bc51ea2f7aafae785..d0c6cee8e4d0d3d3eb2d94acbfd493bb61fe5bba 100644
--- a/content/public/browser/download_item.h
+++ b/content/public/browser/download_item.h
@@ -62,10 +62,6 @@ class CONTENT_EXPORT DownloadItem {
     // Download has been cancelled.
     CANCELLED,
 
-    // This state indicates that the download item is about to be destroyed,
-    // and observers seeing this state should release all references.
-    REMOVING,
-
     // This state indicates that the download has been interrupted.
     INTERRUPTED,
 
@@ -103,10 +99,18 @@ class CONTENT_EXPORT DownloadItem {
   // to receive updates to the download's status.
   class CONTENT_EXPORT Observer {
    public:
-    virtual void OnDownloadUpdated(DownloadItem* download) = 0;
+    virtual void OnDownloadUpdated(DownloadItem* download) {}
 
     // Called when a downloaded file has been opened.
-    virtual void OnDownloadOpened(DownloadItem* download) = 0;
+    virtual void OnDownloadOpened(DownloadItem* download) {}
+
+    // Called when the user removed the download either from UI or at shutdown.

[Randy Smith (Not in Mondays), 2012/07/11 17:55:37]

This implies it's user action that removes the download at shutdown.  More, I
don't think we should remove the download at shutdown.  The abstract download
entity (as opposed to the DownloadItem) is *not* being removed; it'll still be
around when they start up the browser next.

[benjhayden, 2012/07/13 20:03:17]

Done.

+    virtual void OnDownloadRemoved(DownloadItem* download) {}
+
+    // Called when the download is being destroyed. This happens after
+    // every OnDownloadRemoved() as well as when the DownloadManager is going
+    // down.

[Randy Smith (Not in Mondays), 2012/07/11 17:55:37]

These comments have slightly contradictory implications.  If OnDownloadRemoved()
occurs at shutdown, OnDownloadDestroyed() will always be called after
OnDownloadRemoved().

[benjhayden, 2012/07/13 20:03:17]

Done.

+    virtual void OnDownloadDestroyed(DownloadItem* download) {}
 
    protected:
     virtual ~Observer() {}