Add some instrumentation to catch the source of a potential double-free.

content/plugin/npobject_stub.h

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 //
 // A class that receives IPC messages from an NPObjectProxy and calls the real
 // NPObject.
 
 #ifndef CONTENT_PLUGIN_NPOBJECT_STUB_H_
 #define CONTENT_PLUGIN_NPOBJECT_STUB_H_
 #pragma once
 
 #include <vector>
 
+#include "base/debug/stack_trace.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
 #include "content/plugin/npobject_base.h"
 #include "googleurl/src/gurl.h"
 #include "ipc/ipc_channel.h"
 #include "ui/gfx/native_widget_types.h"
 
 class PluginChannelBase;
 struct NPIdentifier_Param;
 struct NPObject;
@@ skipping 54 matching lines @@
                         bool* result);
   void OnInvalidate();
   void OnEnumeration(std::vector<NPIdentifier_Param>* value,
                      bool* result);
   void OnConstruct(const std::vector<NPVariant_Param>& args,
                    IPC::Message* reply_msg);
   void OnEvaluate(const std::string& script, bool popups_allowed,
                   IPC::Message* reply_msg);
 
  private:
+  //----------------------------------------------------------------------------
+  // Temporary code for debugging 94179
+  // TODO(eroman): Delete this when done investigating.
+  //----------------------------------------------------------------------------
+  void CheckIsAlive();
+  static void DeleteSoonHelper(
+      const base::debug::StackTrace& task_origin_stack_trace,
+      NPObjectStub* stub);
+
+  bool has_deletion_stack_trace_;
+  base::debug::StackTrace deletion_stack_trace_;
+
+  // Value to indicate whether this instance is alive or dead.
+  static const int kTokenAlive = 0x1Cd9fe38;
+  static const int kTokenDead = 0xDEADBEEF;
+  int liveness_token_;
+  //----------------------------------------------------------------------------
+
   NPObject* npobject_;
   scoped_refptr<PluginChannelBase> channel_;
   int route_id_;
   gfx::NativeViewId containing_window_;
 
   // The url of the main frame hosting the plugin.
   GURL page_url_;
 };
 
 #endif  // CONTENT_PLUGIN_NPOBJECT_STUB_H_