Bug 730013 - don't addref/release nsTransactionManager so much to prevent it to end up to the purple buffer, r=ehsan

content/html/content/src/nsTextEditorState.cpp

@@ -849,15 +849,11 @@ nsTextInputListener::EditAction()
   nsCOMPtr<nsIEditor> editor;
   frame->GetEditor(getter_AddRefs(editor));
 
-  nsCOMPtr<nsITransactionManager> manager;
-  editor->GetTransactionManager(getter_AddRefs(manager));
-  NS_ENSURE_TRUE(manager, NS_ERROR_FAILURE);
-
   // Get the number of undo / redo items
   PRInt32 numUndoItems = 0;
   PRInt32 numRedoItems = 0;
-  manager->GetNumberOfUndoItems(&numUndoItems);
+  editor->GetNumberOfUndoItems(&numUndoItems);
-  manager->GetNumberOfRedoItems(&numRedoItems);
+  editor->GetNumberOfRedoItems(&numRedoItems);
   if ((numUndoItems && !mHadUndoItems) || (!numUndoItems && mHadUndoItems) ||
       (numRedoItems && !mHadRedoItems) || (!numRedoItems && mHadRedoItems)) {
     // Modify the menu if undo or redo items are different

editor/idl/nsIEditor.idl

@@ -55,7 +55,7 @@ interface nsIEditActionListener;
 interface nsIInlineSpellChecker;
 interface nsITransferable;
 
-[scriptable, uuid(94479B76-7FD7-47D3-BB1E-5B77846339D2)]
+[scriptable, uuid(656005d2-d900-4839-81bf-6274a3c38537)]
 
 interface nsIEditor  : nsISupports
 {
@@ -205,6 +205,16 @@ interface nsIEditor  : nsISupports
     */
   void enableUndo(in boolean enable);
 
+  /**
+   * The number of items on the undo stack.
+   */
+  readonly attribute long numberOfUndoItems;
+
+  /**
+   * The number of items on the redo stack.
+   */
+  readonly attribute long numberOfRedoItems;
+
   /** undo reverses the effects of the last Do operation,
     * if Undo is enabled in the editor.
     * It is provided here so clients need no knowledge of whether

editor/libeditor/base/nsEditor.cpp

@@ -750,6 +750,19 @@ nsEditor::EnableUndo(bool aEnable)
   return NS_OK;
 }
 
+NS_IMETHODIMP
+nsEditor::GetNumberOfUndoItems(PRInt32* aNumItems)
+{
+  *aNumItems = 0;
+  return mTxnMgr ? mTxnMgr->GetNumberOfUndoItems(aNumItems) : NS_OK;
+}
+
+NS_IMETHODIMP
+nsEditor::GetNumberOfRedoItems(PRInt32* aNumItems)
+{
+  *aNumItems = 0;
+  return mTxnMgr ? mTxnMgr->GetNumberOfRedoItems(aNumItems) : NS_OK;
+}
 
 NS_IMETHODIMP
 nsEditor::GetTransactionManager(nsITransactionManager* *aTxnManager)