Relaunch Notification: Add RelaunchHeadsUpPeriod policy

Add ChromeOS specific RelaunchHeadsUpPeriod policy. It will be used to
control time of the first user notification. The exact usage of the
policy and related pref will be added in the subsequent change.

Bug: 963883
Change-Id: Ib8cefc940879a984780987b5fbb1f8a01182b832
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1621922
Commit-Queue: Sergey Poromov <[email protected]>
Reviewed-by: Greg Thompson <[email protected]>
Reviewed-by: David Roger <[email protected]>
Reviewed-by: Sergey Poromov <[email protected]>
Cr-Commit-Position: refs/heads/master@{#662231}
diff --git a/chrome/browser/prefs/browser_prefs.cc b/chrome/browser/prefs/browser_prefs.cc
index 0a97bacf..e0e9d98 100644
--- a/chrome/browser/prefs/browser_prefs.cc
+++ b/chrome/browser/prefs/browser_prefs.cc
@@ -289,6 +289,7 @@
 #include "chrome/browser/ui/webui/chromeos/login/enable_debugging_screen_handler.h"
 #include "chrome/browser/ui/webui/chromeos/login/hid_detection_screen_handler.h"
 #include "chrome/browser/ui/webui/chromeos/login/signin_screen_handler.h"
+#include "chrome/browser/upgrade_detector/upgrade_detector_chromeos.h"
 #include "chromeos/assistant/buildflags.h"
 #include "chromeos/audio/audio_devices_pref_handler_impl.h"
 #include "chromeos/components/account_manager/account_manager.h"
@@ -645,6 +646,7 @@
   policy::PolicyCertServiceFactory::RegisterPrefs(registry);
   policy::TPMAutoUpdateModePolicyHandler::RegisterPrefs(registry);
   quirks::QuirksManager::RegisterPrefs(registry);
+  UpgradeDetectorChromeos::RegisterPrefs(registry);
 #endif
 
 #if defined(OS_MACOSX)