[chromeos] Fix Logout automation when no browser windows are present.

chrome/browser/automation/testing_automation_provider.h

Index: chrome/browser/automation/testing_automation_provider.h
diff --git a/chrome/browser/automation/testing_automation_provider.h b/chrome/browser/automation/testing_automation_provider.h
index 10241259a2ae990412fd67bbce8359925ef4e9b4..46ff91e2565876c4a23416e9faa649c89f9e8711 100644
--- a/chrome/browser/automation/testing_automation_provider.h
+++ b/chrome/browser/automation/testing_automation_provider.h
@@ -1440,7 +1440,7 @@ class TestingAutomationProvider : public AutomationProvider,
                        IPC::Message* reply_message);
 
 #if defined(OS_CHROMEOS)
-  // Login.
+  // Login / Logout.
   void GetLoginInfo(base::DictionaryValue* args, IPC::Message* reply_message);
 
   void ShowCreateAccountUI(base::DictionaryValue* args,
@@ -1463,6 +1463,8 @@ class TestingAutomationProvider : public AutomationProvider,
   void ExecuteJavascriptInOOBEWebUI(
       base::DictionaryValue* args, IPC::Message* reply_message);
 
+  void SignOut(base::DictionaryValue* args, IPC::Message* reply_message);
+
   // Screen locker.
   void LockScreen(base::DictionaryValue* args, IPC::Message* reply_message);