Componentize component_updater: Replace content::BrowserThread usage with task runners

chrome/browser/component_updater/component_updater_configurator.h

 // Copyright (c) 2011 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 CHROME_BROWSER_COMPONENT_UPDATER_COMPONENT_UPDATER_CONFIGURATOR_H_
 #define CHROME_BROWSER_COMPONENT_UPDATER_COMPONENT_UPDATER_CONFIGURATOR_H_
 
 #include <string>
 
+#include "base/memory/ref_counted.h"
+
 class GURL;
 
 namespace base {
 class CommandLine;
+class SingleThreadTaskRunner;
+class SequencedTaskRunner;
 class Version;
 }
 
 namespace net {
 class URLRequestContextGetter;
 }
 
 namespace component_updater {
 
 // Controls the component updater behavior.
@@ skipping 58 matching lines @@
 
   // True means that all ops are performed in this process.
   virtual bool InProcess() const = 0;
 
   // True means that this client can handle delta updates.
   virtual bool DeltasEnabled() const = 0;
 
   // True means that the background downloader can be used for downloading
   // non on-demand components.
   virtual bool UseBackgroundDownloader() const = 0;
+
+  // Gets a task runner to a blocking pool of threads suitable for worker jobs.
+  virtual scoped_refptr<base::SequencedTaskRunner> GetSequencedTaskRunner()
+      const = 0;
+
+  // Gets a task runner for worker jobs guaranteed to run on a single thread.

[blundell, 2014/07/15 08:45:20]

Does there need to be further constraints specified here, e.g., that the task
runner can do IO?

[tommycli, 2014/07/15 18:58:25]

Done.

+  virtual scoped_refptr<base::SingleThreadTaskRunner>
+      GetSingleThreadTaskRunner() const = 0;
 };
 
 Configurator* MakeChromeComponentUpdaterConfigurator(
     const base::CommandLine* cmdline,
     net::URLRequestContextGetter* context_getter);
 
 }  // namespace component_updater
 
 #endif  // CHROME_BROWSER_COMPONENT_UPDATER_COMPONENT_UPDATER_CONFIGURATOR_H_