Add a reboot source for experiment update.

Bug: 180755485
Test: CQ
Change-Id: I0a708a919b23edcc9edb479af1720bcf110c621d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2852162
Reviewed-by: Simeon Anfinrud <sanfin@chromium.org>
Reviewed-by: Luke Halliwell (slow) <halliwell@chromium.org>
Auto-Submit: Yilong Yao <yilongyao@google.com>
Commit-Queue: Yilong Yao <yilongyao@google.com>
Cr-Commit-Position: refs/heads/master@{#876699}

chromecast/public/reboot_shlib.h

@@ -94,6 +94,15 @@ class CHROMECAST_EXPORT RebootShlib {
     // bugs. In that case, business logic can't proceed and busy references
     // can't be trusted, so a dirty reboot will be executed.
     MULTI_SERVICE_BUG = 17,
+
+    // Intentional shutdown by power manager of battery powered devices.
+    POWER_MANAGER_SHUTDOWN = 18,
+
+    // Restart of the Cast component to apply changes due to an experiment flag
+    // value change. This is only used to handle flag changes that would be more
+    // risky to attempt without a full process restart. Very few experiments
+    // trigger this path.
+    EXPERIMENT_CHANGE = 19,
   };
 
   // Initializes any platform-specific reboot systems.

chromecast/system/reboot/reboot_util_core.cc

@@ -46,6 +46,8 @@ bool RebootUtil::IsValidRebootSource(RebootShlib::RebootSource reboot_source) {
     case RebootShlib::RebootSource::GRACEFUL_RESTART:
     case RebootShlib::RebootSource::UNGRACEFUL_RESTART:
     case RebootShlib::RebootSource::MULTI_SERVICE_BUG:
+    case RebootShlib::RebootSource::POWER_MANAGER_SHUTDOWN:
+    case RebootShlib::RebootSource::EXPERIMENT_CHANGE:
       return true;
     default:
       return false;