[Chromedriver] Chromedriver should handle unexpected alert automatically.

chrome/test/chromedriver/chrome/chrome_impl.cc

Index: chrome/test/chromedriver/chrome/chrome_impl.cc
diff --git a/chrome/test/chromedriver/chrome/chrome_impl.cc b/chrome/test/chromedriver/chrome/chrome_impl.cc
index 5cee177811b8dcc99b083f85b47f00a74e2c0297..2933f593a49ad68b2cadf1e4f700fef18302f777 100644
--- a/chrome/test/chromedriver/chrome/chrome_impl.cc
+++ b/chrome/test/chromedriver/chrome/chrome_impl.cc
@@ -154,6 +154,10 @@ std::string ChromeImpl::page_load_strategy() const {
   return page_load_strategy_;
 }
 
+std::string ChromeImpl::UnexpectedAlertBehaviour() const {
+  return unexpected_alert_behaviour_;
+}
+
 Status ChromeImpl::Quit() {
   Status status = QuitImpl();
   if (status.IsOk())
@@ -166,11 +170,13 @@ ChromeImpl::ChromeImpl(
     std::unique_ptr<DevToolsClient> websocket_client,
     ScopedVector<DevToolsEventListener>& devtools_event_listeners,
     std::unique_ptr<PortReservation> port_reservation,
+    std::string unexpected_alert_behaviour,
     std::string page_load_strategy)
     : quit_(false),
       devtools_http_client_(std::move(http_client)),
       devtools_websocket_client_(std::move(websocket_client)),
       port_reservation_(std::move(port_reservation)),
+      unexpected_alert_behaviour_(unexpected_alert_behaviour),
       page_load_strategy_(page_load_strategy) {
   devtools_event_listeners_.swap(devtools_event_listeners);
 }