Add a DCHECK for NULL frame pointers in PasswordAutofillAgent

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 1091 matching lines @@
   if (!password->suggestedValue().isEmpty()) {
       password->setSuggestedValue(blink::WebString());
       password->setAutofilled(was_password_autofilled_);
   }
 }
 
 void PasswordAutofillAgent::ProvisionallySavePassword(
     blink::WebLocalFrame* frame,
     const blink::WebFormElement& form,
     ProvisionallySaveRestriction restriction) {
+  DCHECK(frame);
   scoped_ptr<PasswordForm> password_form(CreatePasswordForm(form));
   if (!password_form || (restriction == RESTRICTION_NON_EMPTY_PASSWORD &&
                          password_form->password_value.empty() &&
                          password_form->new_password_value.empty())) {
     return;
   }
   provisionally_saved_forms_[frame].reset(password_form.release());
 }
 
 }  // namespace autofill