Replace FFmpegDemuxer thread per element with base::TaskScheduler.

media/base/run_all_perftests.cc

 // Copyright 2014 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 "base/bind.h"
+#include "base/task_scheduler/task_scheduler.h"
 #include "base/test/launcher/unit_test_launcher.h"
 #include "base/test/test_suite.h"
 #include "build/build_config.h"
 #include "media/base/media.h"
 
 class TestSuiteNoAtExit : public base::TestSuite {
  public:
   TestSuiteNoAtExit(int argc, char** argv) : TestSuite(argc, argv) {}
   ~TestSuiteNoAtExit() override {}
 
  protected:
   void Initialize() override;
 };
 
 void TestSuiteNoAtExit::Initialize() {
   // Run TestSuite::Initialize first so that logging is initialized.
   base::TestSuite::Initialize();
 
   // Run this here instead of main() to ensure an AtExitManager is already
   // present.
   media::InitializeMediaLibrary();
+
+  base::TaskScheduler::CreateAndSetSimpleTaskScheduler(1);

[gab, 2017/02/23 21:37:09]

For tests see base::test::ScopedTaskScheduler, also you inspired me to make this
documentation clearer https://codereview.chromium.org/2709163006/ :). Anymore
feedback you have on things that were unclear is welcome!

[DaleCurtis, 2017/02/23 23:07:06]

Thanks! Switched, though I think this omits a bit of test coverage since by
forcing an additional thread we get coverage on potential races that the fake
task scheduler will not provide by using the same message loop as the test
control functionality.

[gab, 2017/02/24 01:09:05]

You can use ScopedAsyncTaskScheduler if you want that behavior :).

The reasoning behind ScopedTaskScheduler using the main thread is that it allows
determinism in unit tests (and thus simplicity). IMO fuzzing/testing races is
more the role of browser/integration tests.

 }
 
 int main(int argc, char** argv) {
   TestSuiteNoAtExit test_suite(argc, argv);
 
   // Always run the perf tests serially, to avoid distorting
   // perf measurements with randomness resulting from running
   // in parallel.
   return base::LaunchUnitTestsSerially(
       argc, argv, base::Bind(&TestSuiteNoAtExit::Run,
                              base::Unretained(&test_suite)));
 }