Define EnabledComponentUpdates group policy for the component updater.

chrome/browser/component_updater/supervised_user_whitelist_installer_unittest.cc

 // 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.
 
 #include <stddef.h>
 
 #include "base/bind.h"
 #include "base/callback.h"
 #include "base/files/file_path.h"
 #include "base/files/file_util.h"
@@ skipping 124 matching lines @@
     ADD_FAILURE();
     return false;
   }
 
   std::unique_ptr<ComponentInfo> GetComponentForMimeType(
       const std::string& mime_type) const override {
     return nullptr;
   }
 
   // OnDemandUpdater implementation:
-  bool OnDemandUpdate(const std::string& crx_id) override {
+  void OnDemandUpdate(
+      const std::string& crx_id,
+      ComponentUpdateService::CompletionCallback callback) override {
     on_demand_update_called_ = true;
 
     if (!component_) {
       ADD_FAILURE() << "Trying to update unregistered component " << crx_id;
-      return false;
+      return;
     }
 
     EXPECT_EQ(GetCrxComponentID(*component_), crx_id);
-    return true;
   }
 
  private:
   scoped_refptr<base::SequencedTaskRunner> task_runner_;
   std::unique_ptr<CrxComponent> component_;
   base::Closure registration_callback_;
   bool on_demand_update_called_;
 };
 
 class WhitelistLoadObserver {
@@ skipping 258 matching lines @@
     // but it exercises a different code path.
     profile_attributes_storage()->RemoveProfile(GetProfilePath(kOtherClientId));
     run_loop.RunUntilIdle();
   }
   EXPECT_FALSE(component_update_service_.registered_component());
   EXPECT_FALSE(base::DirectoryExists(whitelist_directory_));
   EXPECT_FALSE(base::PathExists(whitelist_path_));
 }
 
 }  // namespace component_updater