Credential Manager API pops up an auto-signin toast.

chrome/browser/ui/passwords/manage_passwords_ui_controller.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/ui/passwords/manage_passwords_ui_controller.h"
 
 #include "base/auto_reset.h"
 #include "chrome/app/chrome_command_ids.h"
 #include "chrome/browser/browsing_data/browsing_data_helper.h"
 #include "chrome/browser/password_manager/chrome_password_manager_client.h"
@@ skipping 374 matching lines @@
     UpdateBubbleAndIconVisibility();
   }
 }
 
 void ManagePasswordsUIController::ShowBubbleWithoutUserInteraction() {
   DCHECK(should_pop_up_bubble_);
 #if !defined(OS_ANDROID)
   Browser* browser = chrome::FindBrowserWithWebContents(web_contents());
   if (!browser || browser->toolbar_model()->input_in_progress())
     return;
+  if (state_ == password_manager::ui::PENDING_PASSWORD_STATE &&
+      !password_bubble_experiment::ShouldShowBubble(
+          browser->profile()->GetPrefs()))
+    return;

[Mike West, 2015/02/18 22:28:04]

Why do we need this? Don't we just never call into the bubble if we're outside
the experiment?

[vasilii, 2015/02/19 09:37:34]

That's another experiment of showing the "Save" bubble not too often.
This is the line I removed in https://codereview.chromium.org/928753003. I
shouldn't have done that.

   CommandUpdater* updater = browser->command_controller()->command_updater();
   updater->ExecuteCommand(IDC_MANAGE_PASSWORDS_FOR_PAGE);
 #endif
 }
 
 bool ManagePasswordsUIController::PasswordPendingUserDecision() const {
   return state_ == password_manager::ui::PENDING_PASSWORD_STATE;
 }
 
 void ManagePasswordsUIController::WebContentsDestroyed() {
   password_manager::PasswordStore* password_store =
       GetPasswordStore(web_contents());
   if (password_store)
     password_store->RemoveObserver(this);
 }
 
 void ManagePasswordsUIController::SaveForms(
     ScopedVector<autofill::PasswordForm> local_forms,
     ScopedVector<autofill::PasswordForm> federated_forms) {
   form_manager_.reset();
   origin_ = GURL();
   local_credentials_forms_.swap(local_forms);
   federated_credentials_forms_.swap(federated_forms);
   // The map is useless because usernames may overlap.
   password_form_map_.clear();
   new_password_forms_.clear();
 }