[Autofill Auth] Adding nullptr check in AutofillDriver

Ensuring that neither autofill_manager nor client is null when creating InternalAuthenticator instance.
If either is null, then return nullptr (which is already gracefully handled).

Bug: 949269
Change-Id: I217b7c2766675c5cae7a632acd0db16b1a287b3e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2324116Reviewed-by: Tommy Martino <tmartino@chromium.org>
Commit-Queue: Manas Verma <manasverma@google.com>
Cr-Commit-Position: refs/heads/master@{#792750}

components/autofill/content/browser/content_autofill_driver.cc

@@ -109,7 +109,8 @@ bool ContentAutofillDriver::RendererIsAvailable() {
 
 InternalAuthenticator*
 ContentAutofillDriver::GetOrCreateCreditCardInternalAuthenticator() {
-  if (!authenticator_impl_) {
+  if (!authenticator_impl_ && autofill_manager_ &&
+      autofill_manager_->client()) {
     authenticator_impl_ =
         autofill_manager_->client()->CreateCreditCardInternalAuthenticator(
             render_frame_host_);