Bug 1840917 - Add a probe to measure how long it takes to show both the legacy and new migration wizard. data-review=jhirsch,r=tgiles

Differential Revision: https://phabricator.services.mozilla.com/D182389

browser/components/migration/MigrationUtils.sys.mjs

@@ -24,6 +24,7 @@ var gFileMigrators = null;
 var gProfileStartup = null;
 var gL10n = null;
 var gPreviousDefaultBrowserKey = "";
+var gHasOpenedLegacyWizard = false;
 
 let gForceExitSpinResolve = false;
 let gKeepUndoData = false;
@@ -689,6 +690,11 @@ class MigrationUtils {
       return Promise.resolve();
     }
     // Legacy migration dialog
+    if (!gHasOpenedLegacyWizard) {
+      gHasOpenedLegacyWizard = true;
+      aOptions.openedTime = Cu.now();
+    }
+
     const DIALOG_URL = "chrome://browser/content/migration/migration.xhtml";
     let features = "chrome,dialog,modal,centerscreen,titlebar,resizable=no";
     if (AppConstants.platform == "macosx" && !this.isStartupMigration) {