cros: Add app_to_pin_os 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 776 matching lines @@
     UNSET = 0;
     // ARC is not allowed, no data migration needed.
     DISALLOW_ARC = 1;
     // The data migration is allowed, opening the possibility to use ARC.
     ALLOW_MIGRATION = 2;
   };
 
   optional MigrationStrategy migration_strategy = 1;
 }
 
+// An app on Chrome Web Store whose manifest key "required_platform_version"
+// value would be used as the OS pin. Note the app does not have to be present
+// on the device. The pin is applied on the server side.
+message AppToPinOS {
+  optional string app_id = 1;
+}
+
 message ChromeDeviceSettingsProto {
   optional DevicePolicyRefreshRateProto device_policy_refresh_rate = 1;
   optional UserWhitelistProto user_whitelist = 2;
   optional GuestModeEnabledProto guest_mode_enabled = 3;
   optional OBSOLETE_DeviceProxySettingsProto device_proxy_settings = 4
       [deprecated = true];
   optional CameraEnabledProto camera_enabled = 5;
   optional ShowUserNamesOnSigninProto show_user_names = 6;
   optional DataRoamingEnabledProto data_roaming_enabled = 7;
   optional AllowNewUsersProto allow_new_users = 8;
@@ skipping 40 matching lines @@
   optional LoginVideoCaptureAllowedUrlsProto login_video_capture_allowed_urls =
       45;
   optional DeviceLoginScreenAppInstallListProto
       device_login_screen_app_install_list = 46;
   optional NetworkThrottlingEnabledProto network_throttling = 47;
   optional DeviceWallpaperImageProto device_wallpaper_image = 48;
   optional LoginScreenLocalesProto login_screen_locales = 49;
   optional LoginScreenInputMethodsProto login_screen_input_methods = 50;
   optional DeviceEcryptfsMigrationStrategyProto
       device_ecryptfs_migration_strategy = 51;
+  optional AppToPinOS app_to_pin_os = 52;
 }