Autofill: Fix a AutofillProvider crash

Bug: 1145964
Change-Id: I7cf1fbb239ec0a97e69e4d6ea2e15015ecb5fd3b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2521972Reviewed-by: Colin Blundell <blundell@chromium.org>
Commit-Queue: Michael Bai <michaelbai@chromium.org>
Cr-Commit-Position: refs/heads/master@{#824953}

components/autofill/android/provider/autofill_provider_android.cc

@@ -158,7 +158,7 @@ void AutofillProviderAndroid::OnAutofillAvailable(JNIEnv* env,
                                                   jobject jcaller,
                                                   jobject formData) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
-  if (handler_) {
+  if (handler_ && form_) {
     const FormData& form = form_->GetAutofillValues();
     SendFormDataToRenderer(handler_.get(), id_, form);
   }