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

chrome/browser/component_updater/component_updater_configurator.h

Index: chrome/browser/component_updater/component_updater_configurator.h
diff --git a/chrome/browser/component_updater/component_updater_configurator.h b/chrome/browser/component_updater/component_updater_configurator.h
index 49fbf93f267f2190134354974bcdb532686ad37a..fb15462c0f18d54762af24e2b9c456981be58a62 100644
--- a/chrome/browser/component_updater/component_updater_configurator.h
+++ b/chrome/browser/component_updater/component_updater_configurator.h
@@ -7,10 +7,14 @@
 
 #include <string>
 
+#include "base/memory/ref_counted.h"
+
 class GURL;
 
 namespace base {
 class CommandLine;
+class SingleThreadTaskRunner;
+class SequencedTaskRunner;
 class Version;
 }
 
@@ -89,6 +93,14 @@ class Configurator {
   // 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(