Add device policy to disallow shutdown

chrome/browser/chromeos/policy/proto/chrome_device_policy.proto

Index: chrome/browser/chromeos/policy/proto/chrome_device_policy.proto
diff --git a/chrome/browser/chromeos/policy/proto/chrome_device_policy.proto b/chrome/browser/chromeos/policy/proto/chrome_device_policy.proto
index f5c1a4cd9b669076f92b61343f8bb82b52c28458..60fa9b878562bb178a310a373300ec927c9a4551 100644
--- a/chrome/browser/chromeos/policy/proto/chrome_device_policy.proto
+++ b/chrome/browser/chromeos/policy/proto/chrome_device_policy.proto
@@ -583,6 +583,16 @@ message SAMLSettingsProto {
   optional bool transfer_saml_cookies = 1;
 }
 
+message RebootOnShutdownProto {
+  // Determines whether the device automatically reboots whenever the user shuts
+  // it down. If this flag is set to true, shutdown is forbidden and UI elements
+  // trigger a device reboot instead of a power off. This policy affects
+  // shutdowns triggered from the UI only. If the user shuts down the device
+  // using the power button, it will not automatically reboot, even if the
+  // policy is enabled.
+  optional bool reboot_on_shutdown = 1 [default = false];
+}
+
 message ChromeDeviceSettingsProto {
   optional DevicePolicyRefreshRateProto device_policy_refresh_rate = 1;
   optional UserWhitelistProto user_whitelist = 2;
@@ -617,4 +627,5 @@ message ChromeDeviceSettingsProto {
   optional AutoCleanupSettigsProto auto_clean_up_settings = 31;
   optional SystemSettingsProto system_settings = 32;
   optional SAMLSettingsProto saml_settings = 33;
+  optional RebootOnShutdownProto reboot_on_shutdown = 34;
 }