Credential Manager API pops up an auto-signin toast.

chrome/browser/ui/passwords/manage_passwords_ui_controller.cc

Index: chrome/browser/ui/passwords/manage_passwords_ui_controller.cc
diff --git a/chrome/browser/ui/passwords/manage_passwords_ui_controller.cc b/chrome/browser/ui/passwords/manage_passwords_ui_controller.cc
index c98b5e55deb1c2d7f8f2a70457c23eb031cf1fd6..b6eeaefc8266a12250ed5b063ecbec6b427855aa 100644
--- a/chrome/browser/ui/passwords/manage_passwords_ui_controller.cc
+++ b/chrome/browser/ui/passwords/manage_passwords_ui_controller.cc
@@ -392,6 +392,10 @@ void ManagePasswordsUIController::ShowBubbleWithoutUserInteraction() {
   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