Use an interface to get to the C++ object pointer instead of casting directly...

chrome_frame/bind_context_info.cc

 // Copyright (c) 2010 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.
 
 #include "chrome_frame/bind_context_info.h"
 #include "chrome_frame/utils.h"
 
 // This is non const due to API expectations
 static wchar_t* kBindContextInfo = L"_CHROMEFRAME_BIND_CONTEXT_INFO_";
 
 // BindContextInfo member definitions.
 BindContextInfo::BindContextInfo()
     : no_cache_(false),
       chrome_request_(false),
       is_switching_(false) {
 }
 
+BindContextInfo::~BindContextInfo() {
+}
+
 BindContextInfo* BindContextInfo::FromBindContext(IBindCtx* bind_context) {
   if (!bind_context) {
     NOTREACHED();
     return NULL;
   }
 
   ScopedComPtr<IUnknown> context;
   bind_context->GetObjectParam(kBindContextInfo, context.Receive());
   if (context) {
-    return static_cast<BindContextInfo*>(context.get());
+    ScopedComPtr<IBindContextInfoInternal> internal;
+    HRESULT hr = internal.QueryFrom(context);
+    DCHECK(SUCCEEDED(hr));
+    if (SUCCEEDED(hr)) {
+      BindContextInfo* ret = NULL;
+      internal->GetCppObject(reinterpret_cast<void**>(&ret));
+      DCHECK(ret);
+      DLOG_IF(WARNING, reinterpret_cast<void*>(ret) !=
+                       reinterpret_cast<void*>(internal.get()))
+          << "marshalling took place!";
+      return ret;
+    }
   }
 
   CComObject<BindContextInfo>* bind_context_info = NULL;
-  CComObject<BindContextInfo>::CreateInstance(&bind_context_info);
+  HRESULT hr = CComObject<BindContextInfo>::CreateInstance(&bind_context_info);
   DCHECK(bind_context_info != NULL);
+  if (bind_context_info) {
+    bind_context_info->AddRef();
+    hr = CoCreateFreeThreadedMarshaler(bind_context_info->GetUnknown(),
+                                       bind_context_info->ftm_.Receive());
+    DCHECK(bind_context_info->ftm_);
+    if (SUCCEEDED(hr)) {
+      hr = bind_context->RegisterObjectParam(kBindContextInfo,
+                                             bind_context_info);
+    }
 
-  bind_context->RegisterObjectParam(kBindContextInfo, bind_context_info);
+    DCHECK(SUCCEEDED(hr)) << "Failed to initialize BindContextInfo";
+    bind_context_info->Release();
+    if (FAILED(hr))
+      bind_context_info = NULL;
+  }
+
   return bind_context_info;
 }
 
 void BindContextInfo::SetToSwitch(IStream* cache) {
   is_switching_ = true;
   if  (!no_cache_) {
     cache_ = cache;
     RewindStream(cache_);
   }
 }