Revert 198844 "Move sequenced_task_runner to base/task"

Reverting revisions that rely on r198820 so to unbreak the build.

> Move sequenced_task_runner to base/task
> 
> BUG=
> [email protected]
> 
> Review URL: https://codereview.chromium.org/14927008

[email protected]

Review URL: https://codereview.chromium.org/14985007

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@198848 0039d316-1c4b-4281-b951-d872f2087c98
diff --git a/base/single_thread_task_runner.h b/base/single_thread_task_runner.h
index 894bad99..e82941a3 100644
--- a/base/single_thread_task_runner.h
+++ b/base/single_thread_task_runner.h
@@ -6,7 +6,7 @@
 #define BASE_SINGLE_THREAD_TASK_RUNNER_H_
 
 #include "base/base_export.h"
-#include "base/task/sequenced_task_runner.h"
+#include "base/sequenced_task_runner.h"
 
 namespace base {