Add UMA for Grid overlays opened source

Backend CL: https://crrev.com/c/2410069

Bug: chromium:1047356
Change-Id: I42d4b9e933d6d136b6b6f6da5d312cb25d8eff08
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/2410229
Reviewed-by: Changhao Han <[email protected]>
Reviewed-by: Mathias Bynens <[email protected]>
Reviewed-by: Alex Rudenko <[email protected]>
Commit-Queue: Changhao Han <[email protected]>
diff --git a/front_end/elements/LayoutSidebarPane.js b/front_end/elements/LayoutSidebarPane.js
index a6bb941..6f71ca0 100644
--- a/front_end/elements/LayoutSidebarPane.js
+++ b/front_end/elements/LayoutSidebarPane.js
@@ -6,6 +6,7 @@
 // TODO(crbug.com/1011811): Enable TypeScript compiler checks
 
 import * as Common from '../common/common.js';
+import * as Host from '../host/host.js';
 import * as SDK from '../sdk/sdk.js';
 import * as UI from '../ui/ui.js';
 
@@ -32,7 +33,8 @@
       },
       toggle: value => {
         if (value) {
-          node.domModel().overlayModel().highlightGridInPersistentOverlay(node.id);
+          node.domModel().overlayModel().highlightGridInPersistentOverlay(
+              node.id, Host.UserMetrics.GridOverlayOpener.LayoutPane);
         } else {
           node.domModel().overlayModel().hideGridInPersistentOverlay(node.id);
         }