Provide a callback for Component Updater OnDemand calls.

components/component_updater/component_updater_service.h

 // Copyright 2014 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.
 
 #ifndef COMPONENTS_COMPONENT_UPDATER_COMPONENT_UPDATER_SERVICE_H_
 #define COMPONENTS_COMPONENT_UPDATER_COMPONENT_UPDATER_SERVICE_H_
 
 #include <stdint.h>
 
 #include <memory>
@@ skipping 59 matching lines @@
 // be downloaded, verified and unpacked. Then component-specific installer
 // ComponentInstaller::Install (of CrxComponent::installer) will be called.
 //
 // During the normal operation of the component updater some specific
 // notifications are fired, like COMPONENT_UPDATER_STARTED and
 // COMPONENT_UPDATE_FOUND. See notification_type.h for more details.
 //
 // All methods are safe to call ONLY from the browser's main thread.
 class ComponentUpdateService {
  public:
+  using CompletionCallback = update_client::UpdateClient::CompletionCallback;
   using Observer = update_client::UpdateClient::Observer;
 
   // Adds an observer for this class. An observer should not be added more
   // than once. The caller retains the ownership of the observer object.
   virtual void AddObserver(Observer* observer) = 0;
 
   // Removes an observer. It is safe for an observer to be removed while
   // the observers are being notified.
   virtual void RemoveObserver(Observer* observer) = 0;
 
@@ skipping 65 matching lines @@
  private:
   friend class OnDemandTester;
   friend class SupervisedUserWhitelistInstaller;
   friend class ::ComponentsUI;
   friend class ::PluginObserver;
 
   // Triggers an update check for a component. |id| is a value
   // returned by GetCrxComponentID(). If an update for this component is already
   // in progress, the function returns |kInProgress|. If an update is available,
   // the update will be applied. The caller can subscribe to component update
-  // service notifications to get an indication about the outcome of the
-  // on-demand update. The function does not implement any cooldown interval.
-  // TODO(sorin): improve this API so that the result of this non-blocking
-  // call is provided by a callback.
-  virtual bool OnDemandUpdate(const std::string& id) = 0;
+  // service notifications and provide an optional callback to get the result
+  // of the call. The function does not implement any cooldown interval.
+  virtual void OnDemandUpdate(
+      const std::string& id,
+      ComponentUpdateService::CompletionCallback callback) = 0;
 };
 
 // Creates the component updater.
 std::unique_ptr<ComponentUpdateService> ComponentUpdateServiceFactory(
     const scoped_refptr<Configurator>& config);
 
 }  // namespace component_updater
 
 #endif  // COMPONENTS_COMPONENT_UPDATER_COMPONENT_UPDATER_SERVICE_H_