Initialize TaskScheduler in all child processes.

content/child/child_process.cc

Index: content/child/child_process.cc
diff --git a/content/child/child_process.cc b/content/child/child_process.cc
index 7c5b408e842e328c5f0b8c2edc1abe0beb91a41b..19b28b7c5118efff1e539df86169f824dd1bdd69 100644
--- a/content/child/child_process.cc
+++ b/content/child/child_process.cc
@@ -13,6 +13,7 @@
 #include "base/single_thread_task_runner.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/utf_string_conversions.h"
+#include "base/task_scheduler/task_scheduler.h"
 #include "base/threading/thread.h"
 #include "base/threading/thread_local.h"
 #include "build/build_config.h"
@@ -47,6 +48,15 @@ ChildProcess::ChildProcess(base::ThreadPriority io_thread_priority)
 
   base::StatisticsRecorder::Initialize();
 
+  // Initialize TaskScheduler if not already done. A TaskScheduler may already
+  // exist when ChildProcess is instantiated in the browser process or in a
+  // test process.
+  if (!base::TaskScheduler::GetInstance()) {
+    InitializeTaskScheduler();
+    DCHECK(base::TaskScheduler::GetInstance());
+    initialized_task_scheduler_ = true;
+  }
+
   // We can't recover from failing to start the IO thread.
   base::Thread::Options thread_options(base::MessageLoop::TYPE_IO, 0);
   thread_options.priority = io_thread_priority;
@@ -80,6 +90,11 @@ ChildProcess::~ChildProcess() {
 
   g_lazy_tls.Pointer()->Set(NULL);
   io_thread_.Stop();
+
+  if (initialized_task_scheduler_) {
+    DCHECK(base::TaskScheduler::GetInstance());
+    base::TaskScheduler::GetInstance()->Shutdown();
+  }
 }
 
 ChildThreadImpl* ChildProcess::main_thread() {
@@ -162,4 +177,9 @@ void ChildProcess::WaitForDebugger(const std::string& label) {
 #endif  // defined(OS_POSIX)
 }
 
+void ChildProcess::InitializeTaskScheduler() {
+  constexpr int kMaxThreads = 2;
+  base::TaskScheduler::CreateAndSetSimpleTaskScheduler(kMaxThreads);
+}
+
 }  // namespace content