Redirect the MessageLoop's task runner to the renderer scheduler

components/scheduler/child/nestable_single_thread_task_runner.h

Index: components/scheduler/child/nestable_single_thread_task_runner.h
diff --git a/components/scheduler/child/nestable_single_thread_task_runner.h b/components/scheduler/child/nestable_single_thread_task_runner.h
index 0b507a2d254efcb5657c320d5f867fd70679bf80..210f44b4532875eb8fab180ffea00e6e93f65587 100644
--- a/components/scheduler/child/nestable_single_thread_task_runner.h
+++ b/components/scheduler/child/nestable_single_thread_task_runner.h
@@ -17,6 +17,12 @@ class SCHEDULER_EXPORT NestableSingleThreadTaskRunner
  public:
   NestableSingleThreadTaskRunner() {}
 
+  // 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;
+
   // Returns true if the task runner is nested (i.e., running a run loop within
   // a nested task).
   virtual bool IsNested() const = 0;