Bug 522645 - Add flag to indicate that a message is from a feed. r=bienvenu.

mailnews/base/public/nsMsgMessageFlags.idl

@@ -39,6 +39,9 @@ interface nsMsgMessageFlags
   /// The children of this sub-thread are folded in the display
   const nsMsgMessageFlagType Elided          = 0x00000020;
 
+  /// The message is a feed, originally downloaded in a server.type=rss account
+  const nsMsgMessageFlagType FeedMsg         = 0x00000040;
+
   /// This news article or IMAP message is present in the disk cache
   const nsMsgMessageFlagType Offline         = 0x00000080;
 

mailnews/extensions/newsblog/content/FeedItem.js

@@ -380,7 +380,8 @@ FeedItem.prototype =
     msgFolder.gettingNewMessages = true;
     // Source is a unicode string, we want to save a char * string in
     // the original charset. So convert back.
-    folder.addMessage(this.mUnicodeConverter.ConvertFromUnicode(source));
+    let msgDBHdr = folder.addMessage(this.mUnicodeConverter.ConvertFromUnicode(source));
+    msgDBHdr.OrFlags(Ci.nsMsgMessageFlags.FeedMsg);
     msgFolder.gettingNewMessages = false;
   },