Add device policy to disallow shutdown

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

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 syntax = "proto2";
 
 option optimize_for = LITE_RUNTIME;
 
 package enterprise_management;
 
@@ skipping 565 matching lines @@
 }
 
 // Settings that control login for SAML users.
 message SAMLSettingsProto {
   // Whether cookies set by a SAML IdP should be transferred to users' profiles
   // every time a user authenticates via SAML during login. If false, cookies
   // are transferred during each user's first login only.
   optional bool transfer_saml_cookies = 1;
 }
 
+message RebootOnShutdownProto {
+  // Determines whether the device may be shut down. If this flag is set to

[bartfab (slow), 2014/12/15 18:01:56]

Nit: Now that the policy was renamed, I think this comment should be reworded to
something like:

Determines whether the device automatically reboots whenever the user shuts it
down. 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.

[cschuet (SLOW), 2014/12/16 10:02:07]

Done.

+  // true, shutdown is forbidden and UI elements trigger a device reboot instead
+  // of a power off. This policy controls shutdown via the UI only.
+  optional bool reboot_on_shutdown = 1 [default = false];
+}
+
 message ChromeDeviceSettingsProto {
   optional DevicePolicyRefreshRateProto device_policy_refresh_rate = 1;
   optional UserWhitelistProto user_whitelist = 2;
   optional GuestModeEnabledProto guest_mode_enabled = 3;
   optional DeviceProxySettingsProto device_proxy_settings = 4;
   optional CameraEnabledProto camera_enabled = 5;
   optional ShowUserNamesOnSigninProto show_user_names = 6;
   optional DataRoamingEnabledProto data_roaming_enabled = 7;
   optional AllowNewUsersProto allow_new_users = 8;
   optional MetricsEnabledProto metrics_enabled = 9;
@@ skipping 14 matching lines @@
   optional UptimeLimitProto uptime_limit = 24;
   optional VariationsParameterProto variations_parameter = 25;
   optional AttestationSettingsProto attestation_settings = 26;
   optional AccessibilitySettingsProto accessibility_settings = 27;
   optional SupervisedUsersSettingsProto supervised_users_settings = 28;
   optional LoginScreenPowerManagementProto login_screen_power_management = 29;
   optional SystemUse24HourClockProto use_24hour_clock = 30;
   optional AutoCleanupSettigsProto auto_clean_up_settings = 31;
   optional SystemSettingsProto system_settings = 32;
   optional SAMLSettingsProto saml_settings = 33;
+  optional RebootOnShutdownProto reboot_on_shutdown = 34;
 }