[Chrome OS] Add setting for enabling whitelisting to device policy proto

chrome/browser/policy/proto/chrome_device_policy.proto

Index: chrome/browser/policy/proto/chrome_device_policy.proto
diff --git a/chrome/browser/policy/proto/chrome_device_policy.proto b/chrome/browser/policy/proto/chrome_device_policy.proto
index a6cdbe323bc69731f740cd9b4352bf34237e764e..259ab6cd2d2bd428489f294cc56061af31d39cd1 100644
--- a/chrome/browser/policy/proto/chrome_device_policy.proto
+++ b/chrome/browser/policy/proto/chrome_device_policy.proto
@@ -17,6 +17,31 @@ message UserWhitelistProto {
   repeated string user_whitelist = 1;
 }
 
+message AllowNewUsersProto {
+  // Determines whether we allow arbitrary users to log into the device.
+  // Should default to true.
+  // This interacts with the UserWhitelistProto as follows:
+  // allow_new_users | user_whitelist | user_whitelist_size | anyone can log in
+  //-----------------+----------------+---------------------+------------------
+  //  present, true  | not present    | N/A                 | Yes
+  //-----------------+----------------+---------------------+------------------
+  //  present, true  | present        | >= 0                | Yes
+  //-----------------+----------------+---------------------+------------------
+  //  present, false | not present    | N/A                 | (Broken) Yes
+  //-----------------+----------------+---------------------+------------------
+  //  present, false | present        | 0                   | (Broken) Yes
+  //-----------------+----------------+---------------------+------------------
+  //  present, false | present        | > 0                 | No, W/L enforced
+  //-----------------+----------------+---------------------+------------------
+  //  not present    | not present    | N/A                 | Yes
+  //-----------------+----------------+---------------------+------------------
+  //  not present    | present        | 0                   | Yes
+  //-----------------+----------------+---------------------+------------------
+  //  not present    | present        | > 0                 | No, W/L enforced
+  //-----------------+----------------+---------------------+------------------
+  optional bool allow_new_users = 1;

[gfeher, 2011/04/12 16:18:29]

Do I understand correctly, that we only need this field to persist the state of
a checkbox on the GUI, but it is okay if the server never sets it to present?

[Chris Masone, 2011/04/12 16:22:39]

Essentially, yes.  We will use this to persist (and honor) the state of a
checkbox on the GUI, but the server never needs to worry about it.

I will advocate that we move away from the extra checkbox in the future as well,
but for now...this is the path of least resistance.

+}
+
 message GuestModeEnabledProto {
   // Determines if guests are allowed to log in to the device.
   // Should default to true.
@@ -49,4 +74,5 @@ message ChromeDeviceSettingsProto {
   optional DeviceProxySettingsProto device_proxy_settings = 4;
   optional ShowUserNamesOnSigninProto show_user_names = 5;
   optional DataRoamingEnabledProto data_roaming_enabled = 6;
+  optional AllowNewUsersProto allow_new_users = 7;
 }