Redirect the MessageLoop's task runner to the renderer scheduler

components/scheduler/child/scheduler_task_runner_delegate.h

+// Copyright 2015 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.
+
+#ifndef COMPONENTS_SCHEDULER_CHILD_SCHEDULER_TASK_RUNNER_DELEGATE_H_
+#define COMPONENTS_SCHEDULER_CHILD_SCHEDULER_TASK_RUNNER_DELEGATE_H_
+
+#include "base/message_loop/message_loop.h"
+#include "components/scheduler/child/nestable_single_thread_task_runner.h"
+#include "components/scheduler/scheduler_export.h"
+
+namespace scheduler {
+
+class SCHEDULER_EXPORT SchedulerTaskRunnerDelegate
+    : public NestableSingleThreadTaskRunner {
+ public:
+  SchedulerTaskRunnerDelegate() {}
+
+  // If the underlying task runner supports the concept of a default task
+  // runner, the delegate should implement this function to redirect that task
+  // runner to the scheduler.
+  virtual void SetDefaultTaskRunner(
+      scoped_refptr<base::SingleThreadTaskRunner> task_runner) = 0;
+
+  // Similarly this method can be used to restore the original task runner when
+  // the scheduler no longer wants to intercept tasks.
+  virtual void RestoreDefaultTaskRunner() = 0;
+
+ protected:
+  ~SchedulerTaskRunnerDelegate() override {}
+
+  DISALLOW_COPY_AND_ASSIGN(SchedulerTaskRunnerDelegate);
+};
+
+}  // namespace scheduler
+
+#endif  // COMPONENTS_SCHEDULER_CHILD_SCHEDULER_TASK_RUNNER_DELEGATE_H_