Adds a flag to support "Virtual Time" to the blink scheduler

components/scheduler/base/nestable_task_runner_for_test.h

Index: components/scheduler/base/nestable_task_runner_for_test.h
diff --git a/components/scheduler/base/nestable_task_runner_for_test.h b/components/scheduler/base/nestable_task_runner_for_test.h
index 593b846a073595af6549123a62f053bc6b4c9b94..0803ccf5d44775c833ae399c44390d6f4bc7533e 100644
--- a/components/scheduler/base/nestable_task_runner_for_test.h
+++ b/components/scheduler/base/nestable_task_runner_for_test.h
@@ -5,6 +5,7 @@
 #ifndef CONTENT_RENDERER_SCHEDULER_BASE_NESTABLE_TASK_RUNNER_FOR_TEST_H_
 #define CONTENT_RENDERER_SCHEDULER_BASE_NESTABLE_TASK_RUNNER_FOR_TEST_H_
 
+#include "base/time/tick_clock.h"
 #include "components/scheduler/base/nestable_single_thread_task_runner.h"
 
 namespace scheduler {
@@ -12,7 +13,8 @@ namespace scheduler {
 class NestableTaskRunnerForTest : public NestableSingleThreadTaskRunner {
  public:
   static scoped_refptr<NestableTaskRunnerForTest> Create(
-      scoped_refptr<base::SingleThreadTaskRunner> task_runner);
+      scoped_refptr<base::SingleThreadTaskRunner> task_runner,
+      scoped_ptr<base::TickClock> time_source);
 
   // NestableSingleThreadTaskRunner implementation
   bool PostDelayedTask(const tracked_objects::Location& from_here,
@@ -23,14 +25,18 @@ class NestableTaskRunnerForTest : public NestableSingleThreadTaskRunner {
                                   base::TimeDelta delay) override;
   bool RunsTasksOnCurrentThread() const override;
   bool IsNested() const override;
+  base::TimeTicks NowTicks() override;
+  void OnNoMoreWork() override;
 
  protected:
   ~NestableTaskRunnerForTest() override;
   NestableTaskRunnerForTest(
-      scoped_refptr<base::SingleThreadTaskRunner> task_runner);
+      scoped_refptr<base::SingleThreadTaskRunner> task_runner,
+      scoped_ptr<base::TickClock> time_source);
 
  private:
   scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
+  scoped_ptr<base::TickClock> time_source_;
 
   DISALLOW_COPY_AND_ASSIGN(NestableTaskRunnerForTest);
 };