[ChromeDriver] Do not return stale window handle

Bug: chromedriver:1404
Change-Id: Ic4c23921a253584f9b3b29deb7a02398f43f574e
Reviewed-on: https://chromium-review.googlesource.com/c/1289690Reviewed-by: John Chen <johnchen@chromium.org>
Commit-Queue: Tatiana Buldina <buldina@chromium.org>
Cr-Commit-Position: refs/heads/master@{#600982}

chrome/test/chromedriver/session_commands.cc

@@ -474,7 +474,9 @@ Status ExecuteGetCurrentWindowHandle(Session* session,
   Status status = session->GetTargetWindow(&web_view);
   if (status.IsError())
     return status;
-
+  status = web_view->ConnectIfNecessary();
+  if (status.IsError())
+    return status;
   value->reset(new base::Value(WebViewIdToWindowHandle(web_view->GetId())));
   return Status(kOk);
 }