[GRC] UKM Support

services/resource_coordinator/public/interfaces/service_callbacks.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 "components/ukm/public/interfaces/ukm_interface.mojom";
+
+// This class is intended to provide an interface to register mojo interfaces that
+// are not currently accessible to the ResourceCoordinatorService (resource_coordinator)
+// due to software layering issues. For example (and the reason for this interface),
+// the UKM mojo interface lives within the content_browser service which is not accesible

[oystein (OOO til 10th of July), 2017/06/22 20:27:02]

s/accesible/accessible/

I'd reword this a little bit: The interface is accessible, as it's in
//components/; it's just that it's *bound* within content_browser and hence
needs the browser to bind it and then to pass a messagepipe down to the GRC
service.

[matthalp, 2017/06/22 22:59:31]

Done. Let me know if this could be improved further.

+// to anything within services/* as content_browser corresponds to code within chrome/*.
+// As a result, ServiceCallbacks interface is strategically called within content_browser
+// to pass in the initialized UkmRecorderInterfacePtr.
+interface ServiceCallbacks {
+  // Checks to see if the resource_coordinator service is already active. Any call to
+  // EnsureUkmRecorderInterface should be enclosed in the callback and called only
+  // when active == true to avoid creating an excessive number of UkmRecorderInterface
+  // mojo connections as the resource_coordinator service will ignore the UkmRecorderInterface
+  // passed into EnsureUkmRecorderInterface if it is already active.
+  IsUkmRecorderInterfaceInitialized() => (bool ukm_recorder_already_initialized);
+
+  SetUkmRecorderInterface(ukm.mojom.UkmRecorderInterface ukm_recorder_interface);
+};