[GRC] ResourceCoordinatorInterface support to remove children

services/resource_coordinator/public/interfaces/coordination_unit.mojom

 // Copyright 2017 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.
 
 module resource_coordinator.mojom;
 
 import "events.mojom";
 import "mojo/common/values.mojom";
 
 // Any new type here needs to be mirrored between coordination_unit_types.h and
@@ skipping 36 matching lines @@
   SendEvent(Event event);
 
   // Mainly used to force a round-trip to the service over the pipe for
   // a specific unit, so we don't have to deal with possibly-not-yet-created
   // children in AddChild()
   GetID() => (CoordinationUnitID id);
 
   // Add a new binding to an existing CoordinationUnit.
   AddBinding(CoordinationUnit& request);
 
-  // child_id must represent a CU which already exists service-side,
+  // child_id must represent a CU that already exists service-side,
   // and can't be a direct ascendent or descendent of the current unit.
   AddChild(CoordinationUnitID child_id);
+
+  // child_id must represent a CU that already exists service-side
+  // and is a direct descendent of the current unit.
+  RemoveChild(CoordinationUnitID child_id);
   SetCoordinationPolicyCallback(CoordinationPolicyCallback callback);
 
   // Sets a property on the CoordinationUnitImpl's internal key-value store.
   SetProperty(Property property);
 };