Use devtools to set user agent in chromedriver

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 476de991a1218fc52a76d24e4d984fc2cd8c6acd..079975fa7903d8a3222dff36753c38ac300efc03 100644
--- a/chrome/test/chromedriver/chrome/chrome_impl.cc
+++ b/chrome/test/chromedriver/chrome/chrome_impl.cc
@@ -110,7 +110,7 @@ void ChromeImpl::UpdateWebViews(const WebViewsInfo& views_info,
         web_views_.push_back(make_linked_ptr(new WebViewImpl(
             view.id, w3c_compliant, devtools_http_client_->browser_info(),
             std::move(client), devtools_http_client_->device_metrics(),
-            page_load_strategy_)));
+            page_load_strategy_, devtools_http_client_->user_agent())));
       }
     }
   }