A change in the way User Agent is modified caused Chrome Frame to mistakenly disable itself when ...

chrome_frame/http_negotiate.cc

 // 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.
 
 #include "chrome_frame/http_negotiate.h"
 
 #include <atlbase.h>
 #include <atlcom.h>
 #include <htiframe.h>
 
@@ skipping 225 matching lines @@
       // Replace the user-agent header with Chrome's.
       updated_headers = ReplaceOrAddUserAgent(*additional_headers,
                                               http_utils::GetChromeUserAgent());
     } else {
       updated_headers = AppendCFUserAgentString(headers, *additional_headers);
     }
     *additional_headers = reinterpret_cast<wchar_t*>(::CoTaskMemRealloc(
         *additional_headers,
         (updated_headers.length() + 1) * sizeof(wchar_t)));
     lstrcpyW(*additional_headers, ASCIIToWide(updated_headers).c_str());
+  } else {
+    // TODO(erikwright): Remove the user agent if it is present (i.e., because
+    // of PostPlatform setting in the registry).
   }
   return S_OK;
 }