Flush TaskScheduler in content::RunAllBlockingPoolTasksUntilIdle().

content/public/test/test_utils.cc

 // Copyright (c) 2012 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.
 
 #include "content/public/test/test_utils.h"
 
 #include <utility>
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/location.h"
 #include "base/macros.h"
 #include "base/run_loop.h"
 #include "base/single_thread_task_runner.h"
 #include "base/strings/utf_string_conversions.h"
+#include "base/task_scheduler/task_scheduler.h"
 #include "base/threading/sequenced_worker_pool.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "base/values.h"
 #include "build/build_config.h"
 #include "content/common/site_isolation_policy.h"
 #include "content/common/url_schemes.h"
 #include "content/public/browser/browser_child_process_host_iterator.h"
 #include "content/public/browser/notification_service.h"
 #include "content/public/browser/render_frame_host.h"
 #include "content/public/browser/render_process_host.h"
@@ skipping 124 matching lines @@
       base::ThreadTaskRunnerHandle::Get(), FROM_HERE, run_loop.QuitClosure());
   BrowserThread::PostTask(
       thread_id, FROM_HERE,
       base::Bind(&DeferredQuitRunLoop, post_quit_run_loop_to_ui_thread,
                  kNumQuitDeferrals));
   RunThisRunLoop(&run_loop);
 }
 
 void RunAllBlockingPoolTasksUntilIdle() {
   while (true) {
+    // Flush blocking pool tasks.

[robliao, 2017/03/17 01:00:14]

Remove this comment as it's stating what the next line does.

Alternatively, you can have a banner comment that discusses the postcondition of
this function (all inflight tasks are done at the end of this call and enumerate
the sources).

An interesting non-obvious comment would be why we do this with the MessageLoop
in the third section as we've just dealt with the BlockingPool.

[fdoray, 2017/03/31 20:26:04]

Removed unnecessary comment.

I have a few CLs to land:
1. Flush TaskScheduler in RunAllBlockingPoolTasksUntilIdle (this CL).
2. Always use an async TaskScheduler in TestBrowserThreadBundle.
3. Enable redirection of SequencedWorkerPool to TaskScheduler in
TestBrowserThreadBundle.
4. Remove content::BrowserThread::GetBlockingPool()->FlushForTesting(); from
this function.

I'd like to wait until 4. to work on the comments in this function, because
they'll have to be updated anyways.

     content::BrowserThread::GetBlockingPool()->FlushForTesting();
 
+    // Also flush TaskScheduler tasks since all blocking pool call sites are
+    // being migrated to TaskScheduler.
+    base::TaskScheduler::GetInstance()->FlushForTesting();
+
     TaskObserver task_observer;
     base::MessageLoop::current()->AddTaskObserver(&task_observer);
     base::RunLoop().RunUntilIdle();
     base::MessageLoop::current()->RemoveTaskObserver(&task_observer);
 
     if (!task_observer.processed())
       break;
   }
 }
 
@@ skipping 216 matching lines @@
 
 void WebContentsDestroyedWatcher::Wait() {
   run_loop_.Run();
 }
 
 void WebContentsDestroyedWatcher::WebContentsDestroyed() {
   run_loop_.Quit();
 }
 
 }  // namespace content