Start GuestOsSessionTracker in UserSessionInitializer

Ensure GuestOsSessionTracker is started to capture all VM events.

Bug: b/253838039
Change-Id: I31bbb94331347e795f22bfb2863139145ef729a2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3958457
Commit-Queue: Xiyuan Xia <xiyuan@chromium.org>
Auto-Submit: Joel Hockey <joelhockey@chromium.org>
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Reviewed-by: David Munro <davidmunro@google.com>
Cr-Commit-Position: refs/heads/main@{#1060011}

chrome/browser/ash/login/session/user_session_initializer.cc

@@ -23,6 +23,7 @@
 #include "chrome/browser/ash/child_accounts/screen_time_controller_factory.h"
 #include "chrome/browser/ash/crostini/crostini_manager.h"
 #include "chrome/browser/ash/eche_app/eche_app_manager_factory.h"
+#include "chrome/browser/ash/guest_os/guest_os_session_tracker.h"
 #include "chrome/browser/ash/lock_screen_apps/state_controller.h"
 #include "chrome/browser/ash/login/startup_utils.h"
 #include "chrome/browser/ash/phonehub/phone_hub_manager_factory.h"
@@ -227,6 +228,7 @@ void UserSessionInitializer::InitializePrimaryProfileServices(
   }
 
   arc::ArcServiceLauncher::Get()->OnPrimaryUserProfilePrepared(profile);
+  guest_os::GuestOsSessionTracker::GetForProfile(profile);
 
   crostini::CrostiniManager* crostini_manager =
       crostini::CrostiniManager::GetForProfile(profile);