[chromedriver] Fix race where we might not wait for page load after navigating.

chrome/test/chromedriver/chrome/navigation_tracker.cc

Index: chrome/test/chromedriver/chrome/navigation_tracker.cc
diff --git a/chrome/test/chromedriver/chrome/navigation_tracker.cc b/chrome/test/chromedriver/chrome/navigation_tracker.cc
index cd04f819dcd82ff21cad30f63bc51b8845943e52..509b318c44a5c2a9400c4bf04e65cd41b79fdfc9 100644
--- a/chrome/test/chromedriver/chrome/navigation_tracker.cc
+++ b/chrome/test/chromedriver/chrome/navigation_tracker.cc
@@ -126,3 +126,10 @@ void NavigationTracker::OnEvent(DevToolsClient* client,
     scheduled_frame_set_.clear();
   }
 }
+
+Status NavigationTracker::OnCommandSuccess(DevToolsClient* client,
+                                           const std::string& method) {
+  if (method == "Page.navigate")
+    loading_state_ = kLoading;
+  return Status(kOk);
+}