Provide a callback for Component Updater OnDemand calls.

chrome/browser/component_updater/supervised_user_whitelist_installer.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 "chrome/browser/component_updater/supervised_user_whitelist_installer.h"
 
 #include <stddef.h>
 
 #include <map>
 #include <utility>
@@ skipping 624 matching lines @@
       byte = 0;
     }
   }
   return hash;
 }
 
 // static
 void SupervisedUserWhitelistInstaller::TriggerComponentUpdate(
     OnDemandUpdater* updater,
     const std::string& crx_id) {
-  const bool result = updater->OnDemandUpdate(crx_id);
-  DCHECK(result);
+  updater->OnDemandUpdate(crx_id, ComponentUpdateService::CompletionCallback());

[Bernhard Bauer, 2016/08/19 04:13:05]

Could we DCHECK the result in a callback here? If you don't want to add the
overhead for a release build, feel free to pass the null callback if DCHECKs are
compiled out.

[Sorin Jianu, 2016/08/19 04:23:36]

I will try to add the callback. I am not concerned about the overhead, I just
tried to keep the change mechanical for the existing callers, and hopefully,
people would take advantage of the callbacks.

[Sorin Jianu, 2016/08/19 04:43:36]

On a second thought, I prefer solving this in a future change list to keep the
mechanical aspect of this change. The DCHECK is mostly pedantic, as the existing
code returned a hardcoded true in the interesting case.

 }
 
 }  // namespace component_updater