Add "Sign In" button to the account chooser on Aura.

chrome/browser/ui/views/passwords/account_chooser_dialog_view.h

Index: chrome/browser/ui/views/passwords/account_chooser_dialog_view.h
diff --git a/chrome/browser/ui/views/passwords/account_chooser_dialog_view.h b/chrome/browser/ui/views/passwords/account_chooser_dialog_view.h
index 45fe4baf036e2f41f2a706aa25cb23d08e8ca500..27774519601821af615fd2a5ff97d146ef1de5b6 100644
--- a/chrome/browser/ui/views/passwords/account_chooser_dialog_view.h
+++ b/chrome/browser/ui/views/passwords/account_chooser_dialog_view.h
@@ -39,7 +39,9 @@ class AccountChooserDialogView : public views::DialogDelegateView,
   void WindowClosing() override;
 
   // DialogDelegate:
+  bool Accept() override;
   int GetDialogButtons() const override;
+  bool ShouldDefaultButtonBeBlue() const override;
   base::string16 GetDialogButtonLabel(ui::DialogButton button) const override;
 
   // views::View
@@ -59,6 +61,10 @@ class AccountChooserDialogView : public views::DialogDelegateView,
   // A weak pointer to the controller.
   PasswordDialogController* controller_;
   content::WebContents* web_contents_;
+  // The "Sign in" button is shown for one credential only. The variable is
+  // cached because the framework can call GetDialogButtons() after the
+  // controller is gone.
+  bool show_signin_button_;
 
   DISALLOW_COPY_AND_ASSIGN(AccountChooserDialogView);
 };