Disable password autofill upon page load

fix brave/browser-laptop#12489

Auditors: @bridiver, @diracdeltas, @bbondy

patches/master_patch.patch

@@ -1284,6 +1284,22 @@ index 2b38db266f9aa1f4141c8649c021042ede4e5589..ea0387b11f4b00f87596d738c152aa4c
    OSStatus error = keychain_.FindGenericPassword(
        nullptr, strlen(service_name), service_name, strlen(account_name),
        account_name, &password_length, &password_data, NULL);
+diff --git a/components/password_manager/core/browser/password_form_manager.cc b/components/password_manager/core/browser/password_form_manager.cc
+index 8f44c972d18b5e629fc3dd6ef90aacd71197dc29..83c83c7d9d7e4bac08c1504724eac4481f319451 100644
+--- a/components/password_manager/core/browser/password_form_manager.cc
++++ b/components/password_manager/core/browser/password_form_manager.cc
+@@ -717,9 +717,11 @@ void PasswordFormManager::ProcessFrameInternal(
+   } else {
+     // If fill-on-account-select is not enabled, continue with autofilling any
+     // password forms as traditionally has been done.
++#if defined(MUON_CHROMIUM_BUILD)
+     password_manager_->Autofill(driver.get(), observed_form_, best_matches_,
+                                 form_fetcher_->GetFederatedMatches(),
+                                 *preferred_match_, wait_for_username);
++#endif
+   }
+ }
+
 diff --git a/content/app/content_main_runner.cc b/content/app/content_main_runner.cc
 index d2275a49982ec664c30b8b3e6925096cff2af405..50814c64835ac69e1aafe8b31a22f1ceb359faf9 100644
 --- a/content/app/content_main_runner.cc