Use task runner in version_updater_win.cc.

chrome/browser/google/google_update_win.h

Index: chrome/browser/google/google_update_win.h
diff --git a/chrome/browser/google/google_update_win.h b/chrome/browser/google/google_update_win.h
index 33760ca2de5338017075da3875b12b241917cee5..be47f2f3060024d96a10c32964bcdd8a78241117 100644
--- a/chrome/browser/google/google_update_win.h
+++ b/chrome/browser/google/google_update_win.h
@@ -13,10 +13,6 @@
 #include "google_update/google_update_idl.h"
 #include "ui/gfx/native_widget_types.h"
 
-namespace base {
-class SingleThreadTaskRunner;
-}  // namespace base
-
 // These values are used for a histogram. Do not reorder.
 enum GoogleUpdateErrorCode {
   // The upgrade completed successfully (or hasn't been started yet).
@@ -87,14 +83,13 @@ class UpdateCheckDelegate {
   UpdateCheckDelegate() {}
 };
 
-// Begins an asynchronous update check on |task_runner|. If a new version is
+// Begins an asynchronous update check. If a new version is
 // available and |install_update_if_possible| is true, the new version will be
 // automatically downloaded and installed. |elevation_window| is the window
 // which should own any necessary elevation UI. Methods on |delegate| will be
 // invoked on the caller's thread to provide feedback on the operation, with
 // messages localized to |locale| if possible.
 void BeginUpdateCheck(
-    scoped_refptr<base::SingleThreadTaskRunner> task_runner,
     const std::string& locale,
     bool install_update_if_possible,
     gfx::AcceleratedWidget elevation_window,