Fix LoadDataWithBaseUrlTest#testloadDataWithBaseUrlCallsOnPageStarted with PlzNavigate.

content/browser/frame_host/navigator_impl.cc

Index: content/browser/frame_host/navigator_impl.cc
diff --git a/content/browser/frame_host/navigator_impl.cc b/content/browser/frame_host/navigator_impl.cc
index b2533a84e915e1e3650933c5f2ec1a26d4289824..44e9cec153997026879d8c01fa3edb845306261b 100644
--- a/content/browser/frame_host/navigator_impl.cc
+++ b/content/browser/frame_host/navigator_impl.cc
@@ -1175,6 +1175,9 @@ void NavigatorImpl::RequestNavigation(FrameTreeNode* frame_tree_node,
   if (!navigation_request)
     return;  // Navigation was synchronously stopped.
 
+  navigation_request->navigation_handle()->set_base_url_for_data_url(
+      entry.GetBaseURLForDataURL());
+
   // Have the current renderer execute its beforeunload event if needed. If it
   // is not needed then NavigationRequest::BeginNavigation should be directly
   // called instead.