[Chromedriver] Ensure baseURL is 'about:blank' for dummy page on Chrome 60+.

chrome/test/chromedriver/chrome/navigation_tracker_unittest.cc

Index: chrome/test/chromedriver/chrome/navigation_tracker_unittest.cc
diff --git a/chrome/test/chromedriver/chrome/navigation_tracker_unittest.cc b/chrome/test/chromedriver/chrome/navigation_tracker_unittest.cc
index 91ff255a435667ef1ace19ab3e2e346bade82e5f..a66e6175b6c060768362495c7470acd440073445 100644
--- a/chrome/test/chromedriver/chrome/navigation_tracker_unittest.cc
+++ b/chrome/test/chromedriver/chrome/navigation_tracker_unittest.cc
@@ -46,10 +46,13 @@ class DeterminingLoadStateDevToolsClient : public StubDevToolsClient {
       std::unique_ptr<base::DictionaryValue>* result) override {
     if (method == "DOM.getDocument") {
       base::DictionaryValue result_dict;
-      if (has_empty_base_url_)
-        result_dict.SetString("root.baseURL", std::string());
-      else
+      if (has_empty_base_url_) {
+        result_dict.SetString("root.baseURL", "about:blank");
+        result_dict.SetString("root.documentURL", "http://test");
+      } else {
         result_dict.SetString("root.baseURL", "http://test");
+        result_dict.SetString("root.documentURL", "http://test");
+      }
       result->reset(result_dict.DeepCopy());
       return Status(kOk);
     } else if (method == "Runtime.evaluate") {