Allow extension overinstall

chrome/test/automation/automation_messages.h

Index: chrome/test/automation/automation_messages.h
diff --git a/chrome/test/automation/automation_messages.h b/chrome/test/automation/automation_messages.h
index 307fab188ef0d449579b8e37d1f5bd6948db4cce..5ae18e9e94403371c2abda19a2324594079d5846 100644
--- a/chrome/test/automation/automation_messages.h
+++ b/chrome/test/automation/automation_messages.h
@@ -114,9 +114,6 @@ struct ParamTraits<AutomationMsg_ExtensionResponseValues> {
      case AUTOMATION_MSG_EXTENSION_INSTALL_FAILED:
       control = L"AUTOMATION_MSG_EXTENSION_INSTALL_FAILED";
       break;
-     case AUTOMATION_MSG_EXTENSION_ALREADY_INSTALLED:
-      control = L"AUTOMATION_MSG_EXTENSION_ALREADY_INSTALLED";
-      break;
      default:
       control = L"UNKNOWN";
       break;