Track plugin activation time

Summary: Track the time from when the plugin is selected until its `init()` function finishes.

Reviewed By: passy

Differential Revision: D9239750

fbshipit-source-id: 569f236c9d58f70548f1ba6bf31a96047dcc8245

src/PluginContainer.js

@@ -108,6 +108,7 @@ class PluginContainer extends Component<Props, State> {
     if (ref && target) {
       activateMenuItems(ref);
       ref._init();
+      this.props.logger.trackTimeSince(`activePlugin-${ref.id}`);
       this.plugin = ref;
     }
   };