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

components/scheduler/base/nestable_task_runner_for_test.cc

Index: components/scheduler/base/nestable_task_runner_for_test.cc
diff --git a/components/scheduler/base/nestable_task_runner_for_test.cc b/components/scheduler/base/nestable_task_runner_for_test.cc
index 5f20dd4264ecfad9fb6c14ec526035db7dfd640f..f926d06768068830784fbffe01b4f84fcaa7410b 100644
--- a/components/scheduler/base/nestable_task_runner_for_test.cc
+++ b/components/scheduler/base/nestable_task_runner_for_test.cc
@@ -11,13 +11,16 @@ namespace scheduler {
 
 // static
 scoped_refptr<NestableTaskRunnerForTest> NestableTaskRunnerForTest::Create(
-    scoped_refptr<base::SingleThreadTaskRunner> task_runner) {
-  return make_scoped_refptr(new NestableTaskRunnerForTest(task_runner));
+    scoped_refptr<base::SingleThreadTaskRunner> task_runner,
+    scoped_ptr<base::TickClock> time_source) {
+  return make_scoped_refptr(
+      new NestableTaskRunnerForTest(task_runner, time_source.Pass()));
 }
 
 NestableTaskRunnerForTest::NestableTaskRunnerForTest(
-    scoped_refptr<base::SingleThreadTaskRunner> task_runner)
-    : task_runner_(task_runner) {}
+    scoped_refptr<base::SingleThreadTaskRunner> task_runner,
+    scoped_ptr<base::TickClock> time_source)
+    : task_runner_(task_runner), time_source_(time_source.Pass()) {}
 
 NestableTaskRunnerForTest::~NestableTaskRunnerForTest() {}
 
@@ -43,4 +46,10 @@ bool NestableTaskRunnerForTest::IsNested() const {
   return false;
 }
 
+base::TimeTicks NestableTaskRunnerForTest::NowTicks() {
+  return time_source_->NowTicks();
+}
+
+void NestableTaskRunnerForTest::OnNoMoreWork() {}
+
 }  // namespace scheduler