Fix scrollbar leaks by making sure that we decrement the refcnt when Destroy() is called.

bug #101814 r=pavlov

widget/src/beos/nsScrollbar.cpp

@@ -35,14 +35,22 @@
  *
  * ***** END LICENSE BLOCK ***** */
 
+#include "nsISupportsUtils.h"
+#include "nsWidgetsCID.h"
 #include "nsScrollbar.h"
 #include "nsToolkit.h"
 #include "nsGUIEvent.h"
 #include "nsUnitConversion.h"
 
 
+//-------------------------------------------------------------------------
+//
+// nsISupports 
+//
+//-------------------------------------------------------------------------
 NS_IMPL_ADDREF(nsScrollbar)
 NS_IMPL_RELEASE(nsScrollbar)
+NS_IMPL_QUERY_INTERFACE2(nsScrollbar, nsIScrollbar, nsWindow)
 
 //-------------------------------------------------------------------------
 //
@@ -54,6 +62,7 @@ nsScrollbar::nsScrollbar(PRBool aIsVertical) : nsWindow(), nsIScrollbar()
   NS_INIT_REFCNT();
   mOrientation  = (aIsVertical) ? B_VERTICAL : B_HORIZONTAL;
   mLineIncrement = 0;
+  mScrollbar = 0;
   thumb = 0;
 }
 
@@ -69,25 +78,16 @@ nsScrollbar::~nsScrollbar()
 
 
 //-------------------------------------------------------------------------
-//
-// Query interface implementation
-//
+//  Handle Destroy() here so that we properly Release() the instance
+//  and mScrollbar is destroyed by nsWindow::Destroy even though
+//  mScrollbar is non-zero after the call
 //-------------------------------------------------------------------------
-nsresult nsScrollbar::QueryInterface(const nsIID& aIID, void** aInstancePtr)
-{
-    nsresult result = nsWindow::QueryInterface(aIID, aInstancePtr);
-
-    static NS_DEFINE_IID(kInsScrollbarIID, NS_ISCROLLBAR_IID);
-    if (result == NS_NOINTERFACE && aIID.Equals(kInsScrollbarIID)) {
-        *aInstancePtr = (void*) ((nsIScrollbar*)this);
-        NS_ADDREF_THIS();
-        result = NS_OK;
-    }
-
-    return result;
+NS_METHOD nsScrollbar::Destroy() {
+	nsWindow::Destroy();
+	NS_RELEASE_THIS();
+	return NS_OK;
 }
 
-
 //-------------------------------------------------------------------------
 //
 // Define the range settings 

widget/src/beos/nsScrollbar.h

@@ -38,6 +38,7 @@
 #ifndef nsScrollbar_h__
 #define nsScrollbar_h__
 
+#include "nsISupportsUtils.h"
 #include "nsdefs.h"
 #include "nsWindow.h"
 #include "nsSwitchToUIThread.h"
@@ -49,22 +50,21 @@
 class nsScrollbarBeOS;
 
 /**
- * Native WIN32 scrollbar wrapper. 
+ * Native BeOS scrollbar wrapper. 
  */
 
 class nsScrollbar : public nsWindow,
                     public nsIScrollbar
 {
 
+    // nsISupports
+    NS_DECL_ISUPPORTS
+
 public:
                             nsScrollbar(PRBool aIsVertical);
     virtual                 ~nsScrollbar();
 
-      // nsISupports
-    NS_IMETHOD QueryInterface(REFNSIID aIID, void** aInstancePtr);                           
-    NS_IMETHOD_(nsrefcnt) AddRef(void);                                       
-    NS_IMETHOD_(nsrefcnt) Release(void);          
-
+    NS_IMETHOD Destroy(void);
     // nsIScrollBar implementation
     NS_IMETHOD SetMaxRange(PRUint32 aEndRange);
     NS_IMETHOD GetMaxRange(PRUint32& aMaxRange);