Fix renderer crashes when frame gets detached while injectng user scripts.

components/autofill/content/renderer/password_autofill_agent.cc

 // Copyright 2013 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 "components/autofill/content/renderer/password_autofill_agent.h"
 
 #include "base/bind.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/message_loop/message_loop.h"
 #include "base/metrics/histogram.h"
@@ skipping 341 matching lines @@
 }
 
 void PasswordAutofillAgent::OnDynamicFormsSeen(blink::WebFrame* frame) {
   SendPasswordForms(frame, false /* only_visible */);
 }
 
 void PasswordAutofillAgent::SendPasswordForms(blink::WebFrame* frame,
                                               bool only_visible) {
   // Make sure that this security origin is allowed to use password manager.
   blink::WebSecurityOrigin origin = frame->document().securityOrigin();
-  if (!OriginCanAccessPasswordManager(origin))
+  if (origin.isNull() || !OriginCanAccessPasswordManager(origin))
     return;
 
   // Checks whether the webpage is a redirect page or an empty page.
   if (IsWebpageEmpty(frame))
     return;
 
   blink::WebVector<blink::WebFormElement> forms;
   frame->document().forms(forms);
 
   std::vector<PasswordForm> password_forms;
@@ skipping 497 matching lines @@
 }
 
 PasswordAutofillAgent::AutofillWebUserGestureHandler::
     AutofillWebUserGestureHandler(PasswordAutofillAgent* agent)
     : agent_(agent) {}
 
 PasswordAutofillAgent::AutofillWebUserGestureHandler::
     ~AutofillWebUserGestureHandler() {}
 
 }  // namespace autofill