Upstream RunBlockingPoolTask().

content/public/test/test_utils.h

Index: content/public/test/test_utils.h
diff --git a/content/public/test/test_utils.h b/content/public/test/test_utils.h
index bf3e1f8d62f7b14fcc60ef3100bff6ff3592b249..9896482037d357d813c9b3b0c7a25ffac2a40dc3 100644
--- a/content/public/test/test_utils.h
+++ b/content/public/test/test_utils.h
@@ -18,7 +18,7 @@
 
 namespace base {
 class Value;
-}
+}  // namespace base
 
 // A collection of functions designed for use with unit and browser tests.
 
@@ -44,6 +44,15 @@ void RunAllPendingInMessageLoop();
 // thread |thread_id| have been processed.
 void RunAllPendingInMessageLoop(BrowserThread::ID thread_id);
 
+// Runs all tasks posted to the blocking pool, including subsequent tasks posted

[sky, 2014/07/11 16:37:54]

You're description seems overly complicated, maybe:
Runs until both the blocking pool and the current message loop are empty (have
no more scheduled tasks).

[mtomasz, 2014/07/14 07:33:57]

Done.

+// to the UI message loop and the blocking pool.
+//
+// A task is often posted to the blocking pool with PostTaskAndReply(). In
+// that case, a task is posted back to the UI message loop, which can again
+// post a task to the blocking pool. This function processes these tasks
+// repeatedly.
+void RunAllBlockingPoolTasksUntilIdle();
+
 // Get task to quit the given RunLoop. It allows a few generations of pending
 // tasks to run as opposed to run_loop->QuitClosure().
 base::Closure GetQuitTaskForRunLoop(base::RunLoop* run_loop);