PasswordAutofillAgent: avoid NULL frames in provisionally_saved_forms_

components/autofill/content/renderer/password_autofill_agent.cc

Index: components/autofill/content/renderer/password_autofill_agent.cc
diff --git a/components/autofill/content/renderer/password_autofill_agent.cc b/components/autofill/content/renderer/password_autofill_agent.cc
index 8797971ab7c53c8074243fe9905c11454d2fca5d..17ef3d72d851535cab3acd9dabf6e2e8546d1d15 100644
--- a/components/autofill/content/renderer/password_autofill_agent.cc
+++ b/components/autofill/content/renderer/password_autofill_agent.cc
@@ -1217,7 +1217,14 @@ void PasswordAutofillAgent::ProvisionallySavePassword(
     blink::WebLocalFrame* frame,
     const blink::WebFormElement& form,
     ProvisionallySaveRestriction restriction) {
-  DCHECK(frame);
+  // TODO(vabr): This is just to stop getting a NULL frame in
+  // |provisionally_saved_forms_|. Cases where we try to save password for a
+  // form in a NULL frame should not happen, and it's currently unclear how they
+  // happen (http://crbug.com/420519). This thing will be hopefully solved by
+  // migrating the PasswordAutofillAgent to observe frames directly
+  // (http://crbug.com/400186).
+  if (!frame)
+    return;
   scoped_ptr<PasswordForm> password_form(CreatePasswordForm(form));
   if (!password_form || (restriction == RESTRICTION_NON_EMPTY_PASSWORD &&
                          password_form->password_value.empty() &&