Adding a driver check in PasswordGenerationPopupControllerImpl::

PasswordAccepted.

Having this check ensures there is no nullptr dereference in case the
driver is deleted and the browser process is not aware of it (i.e.
in case when the renderer is compromised).

Bug: 1133635
Change-Id: Ieee8c2200a4b323af39f730011e733b74e8bc911
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2440095
Commit-Queue: Maria Kazinova <kazinova@google.com>
Reviewed-by: Jan Wilken Dörrie <jdoerrie@chromium.org>
Reviewed-by: Peter Boström <pbos@chromium.org>
Cr-Commit-Position: refs/heads/master@{#812695}

chrome/browser/ui/passwords/password_generation_popup_controller_impl.cc

@@ -194,6 +194,7 @@ void PasswordGenerationPopupControllerImpl::PasswordAccepted() {
     return;
 
   base::WeakPtr<PasswordGenerationPopupControllerImpl> weak_this = GetWeakPtr();
+  CHECK(driver_);
   driver_->GeneratedPasswordAccepted(form_data_, generation_element_id_,
                                      current_password_);
   // |this| can be destroyed here because GeneratedPasswordAccepted pops up