Added policy for disabling locally managed users.

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

Index: chrome/browser/policy/proto/chromeos/chrome_device_policy.proto
diff --git a/chrome/browser/policy/proto/chromeos/chrome_device_policy.proto b/chrome/browser/policy/proto/chromeos/chrome_device_policy.proto
index 5d83a8a682f66209e041b00018a5a90b69982b61..6194616f35263f95f532978ba7dbd4f45530e8f7 100644
--- a/chrome/browser/policy/proto/chromeos/chrome_device_policy.proto
+++ b/chrome/browser/policy/proto/chromeos/chrome_device_policy.proto
@@ -347,6 +347,11 @@ message AttestationSettingsProto {
   optional bool attestation_enabled = 1;
 }
 
+message LocallyManagedUsersSettingsProto {
+  // Defines whether locally managed users can be created on the device.
+  optional bool locally_managed_users_enabled = 1;
+}
+
 message ChromeDeviceSettingsProto {
   optional DevicePolicyRefreshRateProto device_policy_refresh_rate = 1;
   optional UserWhitelistProto user_whitelist = 2;
@@ -374,4 +379,5 @@ message ChromeDeviceSettingsProto {
   optional UptimeLimitProto uptime_limit = 24;
   optional VariationsParameterProto variations_parameter = 25;
   optional AttestationSettingsProto attestation_settings = 26;
+  optional LocallyManagedUsersSettingsProto locally_managed_users_settings = 27;
 }