From 21fabde48a69423c8c89bd77dc56459ec150b99b Mon Sep 17 00:00:00 2001
From: Jim Mathies <jmathies@mozilla.com>
Date: Fri, 4 Feb 2011 14:51:27 -0500
Subject: [PATCH] Bug 630697 - Flash crash [@ _SEH_prolog ]; r=bsmedberg
 a=blocking-final+

---
 dom/plugins/PluginInstanceChild.cpp | 20 ++++++++++++++------
 1 file changed, 14 insertions(+), 6 deletions(-)

diff --git a/dom/plugins/PluginInstanceChild.cpp b/dom/plugins/PluginInstanceChild.cpp
index 5db10429ec..48dbf5a84a 100644
--- a/dom/plugins/PluginInstanceChild.cpp
+++ b/dom/plugins/PluginInstanceChild.cpp
@@ -1393,9 +1393,13 @@ PluginInstanceChild::SetWindowLongAHook(HWND hWnd,
         GetProp(hWnd, kPluginInstanceChildProperty));
 
     // Hook our subclass back up, just like we do on setwindow.   
-    self->mPluginWndProc =
-        reinterpret_cast<WNDPROC>(sUser32SetWindowLongAHookStub(hWnd, nIndex,
-            reinterpret_cast<LONG_PTR>(PluginWindowProc)));
+    WNDPROC currentProc =
+        reinterpret_cast<WNDPROC>(GetWindowLongPtr(hWnd, GWLP_WNDPROC));
+    if (currentProc != PluginWindowProc) {
+        self->mPluginWndProc =
+            reinterpret_cast<WNDPROC>(sUser32SetWindowLongAHookStub(hWnd, nIndex,
+                reinterpret_cast<LONG_PTR>(PluginWindowProc)));
+    }
     return proc;
 }
 
@@ -1422,9 +1426,13 @@ PluginInstanceChild::SetWindowLongWHook(HWND hWnd,
         GetProp(hWnd, kPluginInstanceChildProperty));
 
     // Hook our subclass back up, just like we do on setwindow.   
-    self->mPluginWndProc =
-        reinterpret_cast<WNDPROC>(sUser32SetWindowLongWHookStub(hWnd, nIndex,
-            reinterpret_cast<LONG_PTR>(PluginWindowProc)));
+    WNDPROC currentProc =
+        reinterpret_cast<WNDPROC>(GetWindowLongPtr(hWnd, GWLP_WNDPROC));
+    if (currentProc != PluginWindowProc) {
+        self->mPluginWndProc =
+            reinterpret_cast<WNDPROC>(sUser32SetWindowLongAHookStub(hWnd, nIndex,
+                reinterpret_cast<LONG_PTR>(PluginWindowProc)));
+    }
     return proc;
 }
 
-- 
2.11.4.GIT