[chromedriver] Return not-implemented status code for FullscreenWindow command.

chrome/test/chromedriver/server/http_handler.cc

Index: chrome/test/chromedriver/server/http_handler.cc
diff --git a/chrome/test/chromedriver/server/http_handler.cc b/chrome/test/chromedriver/server/http_handler.cc
index 2c5426c4e4a034c0ac2095af1e3216de3767773d..af0c443b22fb6542d07084f487a7f7092284518c 100644
--- a/chrome/test/chromedriver/server/http_handler.cc
+++ b/chrome/test/chromedriver/server/http_handler.cc
@@ -341,6 +341,11 @@ HttpHandler::HttpHandler(
           kPost,
           "session/:sessionId/window/:windowHandle/maximize",
           WrapToCommand("MaximizeWindow", base::Bind(&ExecuteMaximizeWindow))),
+      CommandMapping(
+          kPost,
+          "session/:sessionId/window/fullscreen",
+          WrapToCommand("FullscreenWindow",
+                        base::Bind(&ExecuteUnimplementedCommand))),
       CommandMapping(kDelete,
                      "session/:sessionId/window",
                      WrapToCommand("CloseWindow", base::Bind(&ExecuteClose))),