Emit error events if the loading of an object element failed

components/plugins/renderer/loadable_plugin_placeholder.h

Index: components/plugins/renderer/loadable_plugin_placeholder.h
diff --git a/components/plugins/renderer/loadable_plugin_placeholder.h b/components/plugins/renderer/loadable_plugin_placeholder.h
index ea52ae9e5d68ab9b1e4418d250b90edc6828163d..a063c18db835557c6555cab374b7823bb9291378 100644
--- a/components/plugins/renderer/loadable_plugin_placeholder.h
+++ b/components/plugins/renderer/loadable_plugin_placeholder.h
@@ -45,7 +45,10 @@ class LoadablePluginPlaceholder : public PluginPlaceholderBase {
   // When we load the plugin, use this already-created plugin, not a new one.
   void SetPremadePlugin(content::PluginInstanceThrottler* throttler);
 
-  void AllowLoading() { allow_loading_ = true; }
+  void AllowLoading() {
+    plugin()->unmarkAsErrorPlaceholder();
+    allow_loading_ = true;
+  }
 
  protected:
   LoadablePluginPlaceholder(content::RenderFrame* render_frame,