add support for downloading all msgs for offline r=naving, sr=sspitzer 15865

mailnews/base/public/nsIMsgFolder.idl

@@ -344,7 +344,7 @@ const nsMsgBiffState nsMsgBiffState_Unknown = 2; // We dunno whether there is ne
   nsIFileChannel getOfflineFileChannel(in nsMsgKey msgKey);
   void DownloadMessagesForOffline(in nsISupportsArray messages);        
 	nsIMsgFolder getChildWithURI(in string uri, in boolean deep);
-
+  void downloadAllForOffline(in nsIUrlListener listener, in nsIMsgWindow window);
 	/**
 	 *	Turn notifications on/off for various notification types. Currently only supporting
 	 *  allMessageCountNotifications which refers to both total and unread message counts.

mailnews/base/util/nsMsgDBFolder.cpp

@@ -566,6 +566,12 @@ NS_IMETHODIMP nsMsgDBFolder:: DownloadMessagesForOffline(nsISupportsArray *messa
   return NS_OK;
 }
 
+NS_IMETHODIMP nsMsgDBFolder:: DownloadAllForOffline(nsIUrlListener *listener, nsIMsgWindow *msgWindow)
+{
+  NS_ASSERTION(PR_FALSE, "imap and news need to override this");
+  return NS_OK;
+}
+
 nsresult nsMsgDBFolder::GetOfflineStoreInputStream(nsIInputStream **stream)
 {
   nsresult rv = NS_ERROR_NULL_POINTER;

mailnews/base/util/nsMsgDBFolder.h

@@ -96,6 +96,7 @@ public:
   NS_IMETHOD GetOfflineFileChannel(nsMsgKey msgKey, nsIFileChannel **aFileChannel);
   NS_IMETHOD HasMsgOffline(nsMsgKey msgKey, PRBool *result);
   NS_IMETHOD DownloadMessagesForOffline(nsISupportsArray *messages);
+  NS_IMETHOD DownloadAllForOffline(nsIUrlListener *listener, nsIMsgWindow *msgWindow);
   NS_IMETHOD GetRetentionSettings(nsIMsgRetentionSettings **settings);
   NS_IMETHOD SetRetentionSettings(nsIMsgRetentionSettings *settings);