Deprecate the unused AutoCleanupSettigsProto.clean_up_strategy policy.

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 543 matching lines @@
   //                       dimmed or soon after the screen has been turned off",
   //       "type": "integer",
   //       "minimum": 0
   //     }
   //   }
   // }
   optional string login_screen_power_management = 1;
 }
 
 message AutoCleanupSettigsProto {
-  // Configures strategy for automatic clean-up process that is run when device
-  // runs out of free disk space. One of "remove-lru", "remove-lru-if-dormant".
+  // Deprecated.  There is only one disk-full cleanup strategy: LRU.
   optional string clean_up_strategy = 1;
 }
 
 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;
@@ skipping 16 matching lines @@
   optional StartUpFlagsProto start_up_flags = 23;
   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;
 }