diff --git a/toolkit/components/autocomplete/public/nsIAutoCompleteResult.idl b/toolkit/components/autocomplete/public/nsIAutoCompleteResult.idl
index 5851d181c74..6abea5a1062 100644
--- a/toolkit/components/autocomplete/public/nsIAutoCompleteResult.idl
+++ b/toolkit/components/autocomplete/public/nsIAutoCompleteResult.idl
@@ -37,7 +37,7 @@
 
 #include "nsISupports.idl"
 
-[scriptable, uuid(44864910-332C-46b0-A4F9-14A301DBCA80)]
+[scriptable, uuid(eb43e1dc-2060-4d8e-aebf-3efec4e21cf8)]
 interface nsIAutoCompleteResult : nsISupports
 {
   /**
@@ -87,4 +87,11 @@ interface nsIAutoCompleteResult : nsISupports
    * Get the style hint for the result at the given index
    */
   AString getStyleAt(in long index);
+
+  /**
+   * Remove the value at the given index from the autocomplete results.
+   * If removeFromDb is set to true, the value should be removed from
+   * persistent storage as well.
+   */
+  void removeValueAt(in long rowIndex, in boolean removeFromDb);
 };
diff --git a/toolkit/components/autocomplete/public/nsIAutoCompleteResultTypes.idl b/toolkit/components/autocomplete/public/nsIAutoCompleteResultTypes.idl
index a09ebc0f236..44a3f36b21c 100755
--- a/toolkit/components/autocomplete/public/nsIAutoCompleteResultTypes.idl
+++ b/toolkit/components/autocomplete/public/nsIAutoCompleteResultTypes.idl
@@ -49,7 +49,7 @@ native mdb_scope(mdb_scope);
 native mdb_column(mdb_column);
 
 /* noscript */
-[uuid(c5257f44-b4d0-41aa-a50b-5b7bcefcc235)]
+[uuid(e6396544-921d-4776-aa62-8bf2dc1ae058)]
 interface nsIAutoCompleteBaseResult : nsIAutoCompleteResult
 {
   void setSearchString(in AString searchString);
@@ -73,8 +73,6 @@ interface nsIAutoCompleteMdbResult : nsIAutoCompleteBaseResult
 
   void addRow(in nsIMdbRow row);
 
-  void removeRowAt(in unsigned long rowIndex, in boolean removeFromDb);
-
   nsIMdbRow getRowAt(in unsigned long rowIndex);
 
   AString getRowValue(in nsIMdbRow row, in mdb_column col);
diff --git a/toolkit/components/autocomplete/src/nsAutoCompleteController.cpp b/toolkit/components/autocomplete/src/nsAutoCompleteController.cpp
index eaa951783b9..212c99448d1 100644
--- a/toolkit/components/autocomplete/src/nsAutoCompleteController.cpp
+++ b/toolkit/components/autocomplete/src/nsAutoCompleteController.cpp
@@ -352,16 +352,9 @@ nsAutoCompleteController::HandleDelete(PRBool *_retval)
   nsAutoString search;
   mInput->GetSearchParam(search);
 
-  nsAutoString value;
-  result->GetValueAt(rowIndex, value);
-
-  nsCOMPtr<nsIAutoCompleteMdbResult> mdbResult(do_QueryInterface(result));
-  if (mdbResult) {
-    // Clear the row in our result and in the DB.
-    mdbResult->RemoveRowAt(rowIndex, PR_TRUE);
-
-    --mRowCount;
-  }
+  // Clear the row in our result and in the DB.
+  result->RemoveValueAt(rowIndex, PR_TRUE);
+  --mRowCount;
 
   // Unselect the current item.
   popup->SetSelectedIndex(-1);
diff --git a/toolkit/components/autocomplete/src/nsAutoCompleteMdbResult.cpp b/toolkit/components/autocomplete/src/nsAutoCompleteMdbResult.cpp
index 748c71309e7..d86f7d6e982 100644
--- a/toolkit/components/autocomplete/src/nsAutoCompleteMdbResult.cpp
+++ b/toolkit/components/autocomplete/src/nsAutoCompleteMdbResult.cpp
@@ -210,7 +210,7 @@ nsAutoCompleteMdbResult::AddRow(nsIMdbRow *aRow)
 }
 
 NS_IMETHODIMP
-nsAutoCompleteMdbResult::RemoveRowAt(PRUint32 aRowIndex, PRBool aRemoveFromDb)
+nsAutoCompleteMdbResult::RemoveValueAt(PRInt32 aRowIndex, PRBool aRemoveFromDb)
 {
   nsIMdbRow *row = mResults.ObjectAt(aRowIndex);
   NS_ENSURE_TRUE(row, NS_ERROR_INVALID_ARG);
diff --git a/toolkit/components/history/src/nsGlobalHistory.cpp b/toolkit/components/history/src/nsGlobalHistory.cpp
index c6835fe61c4..fd8af3b079d 100644
--- a/toolkit/components/history/src/nsGlobalHistory.cpp
+++ b/toolkit/components/history/src/nsGlobalHistory.cpp
@@ -4177,7 +4177,7 @@ nsGlobalHistory::AutoCompleteSearch(const nsAString &aSearchString,
       aPrevResult->GetValueAt(i, url);
       
       if (!AutoCompleteCompare(url, aSearchString, aExclude))
-        aPrevResult->RemoveRowAt(i, PR_FALSE);
+        aPrevResult->RemoveValueAt(i, PR_FALSE);
     }
     
     *aResult = aPrevResult;
diff --git a/toolkit/components/passwordmgr/base/nsPasswordManager.cpp b/toolkit/components/passwordmgr/base/nsPasswordManager.cpp
index 546dbf8159a..2e9675dc949 100644
--- a/toolkit/components/passwordmgr/base/nsPasswordManager.cpp
+++ b/toolkit/components/passwordmgr/base/nsPasswordManager.cpp
@@ -1290,20 +1290,23 @@ nsPasswordManager::HandleEvent(nsIDOMEvent* aEvent)
 class UserAutoComplete : public nsIAutoCompleteResult
 {
 public:
-  UserAutoComplete(const nsAString& aSearchString);
+  UserAutoComplete(const nsACString& aHost, const nsAString& aSearchString);
   virtual ~UserAutoComplete();
 
   NS_DECL_ISUPPORTS
   NS_DECL_NSIAUTOCOMPLETERESULT
 
   nsVoidArray mArray;
-  nsString mSearchString;
-  PRInt32 mDefaultIndex;
-  PRUint16 mResult;
+  nsCString   mHost;
+  nsString    mSearchString;
+  PRInt32     mDefaultIndex;
+  PRUint16    mResult;
 };
   
-UserAutoComplete::UserAutoComplete(const nsAString& aSearchString)
-  : mSearchString(aSearchString),
+UserAutoComplete::UserAutoComplete(const nsACString& aHost,
+                                   const nsAString& aSearchString)
+  : mHost(aHost),
+    mSearchString(aSearchString),
     mDefaultIndex(-1),
     mResult(RESULT_FAILURE)
 {
@@ -1373,6 +1376,20 @@ UserAutoComplete::GetStyleAt(PRInt32 aIndex, nsAString& aHint)
   return NS_OK;
 }
 
+NS_IMETHODIMP
+UserAutoComplete::RemoveValueAt(PRInt32 aIndex, PRBool aRemoveFromDB)
+{
+  NS_ENSURE_TRUE(aIndex >= 0 && aIndex < mArray.Count(), NS_ERROR_INVALID_ARG);
+
+  PRUnichar *user = NS_STATIC_CAST(PRUnichar*, mArray.ElementAt(aIndex));
+  if (aRemoveFromDB)
+    sPasswordManager->RemoveUser(mHost, nsDependentString(user));
+
+  nsMemory::Free(user);
+  mArray.RemoveElementAt(aIndex);
+  return NS_OK;
+}
+
 PR_STATIC_CALLBACK(int)
 SortPRUnicharComparator(const void* aElement1,
                         const void* aElement2,
@@ -1426,7 +1443,7 @@ nsPasswordManager::AutoCompleteSearch(const nsAString& aSearchString,
 
     // Get all of the matches into an array that we can sort.
 
-    result = new UserAutoComplete(aSearchString);
+    result = new UserAutoComplete(realm, aSearchString);
 
     SignonHashEntry* hashEnt;
     if (mSignonTable.Get(realm, &hashEnt)) {
diff --git a/toolkit/components/satchel/src/nsFormHistory.cpp b/toolkit/components/satchel/src/nsFormHistory.cpp
index 8bd4e6c17a4..06b3331f9e0 100644
--- a/toolkit/components/satchel/src/nsFormHistory.cpp
+++ b/toolkit/components/satchel/src/nsFormHistory.cpp
@@ -705,7 +705,7 @@ nsFormHistory::AutoCompleteSearch(const nsAString &aInputName,
       nsIMdbRow *row;
       result->GetRowAt(i, &row);
       if (!RowMatch(row, aInputName, aInputValue, nsnull))
-        result->RemoveRowAt(i, PR_FALSE);
+        result->RemoveValueAt(i, PR_FALSE);
     }
   } else {
     result = do_CreateInstance("@mozilla.org/autocomplete/mdb-result;1");