[cherrypick] Fix computation of runtime for throttled tasks

components/scheduler/renderer/throttling_helper_unittest.cc

Index: components/scheduler/renderer/throttling_helper_unittest.cc
diff --git a/components/scheduler/renderer/throttling_helper_unittest.cc b/components/scheduler/renderer/throttling_helper_unittest.cc
index f52a605aa1f5717a09eca22f0f33776b70117580..2936d4380bd45016df6ebf0a1f66acd4f50d58df 100644
--- a/components/scheduler/renderer/throttling_helper_unittest.cc
+++ b/components/scheduler/renderer/throttling_helper_unittest.cc
@@ -276,4 +276,34 @@ TEST_F(ThrottlingHelperTest,
                   base::TimeTicks() + base::TimeDelta::FromSeconds(16)));
 }
 
+TEST_F(ThrottlingHelperTest, TaskDelayIsBasedOnRealTime) {
+  std::vector<base::TimeTicks> run_times;
+
+  throttling_helper_->IncreaseThrottleRefCount(timer_queue_.get());
+
+  // Post an initial task that should run at the first aligned time period.
+  timer_queue_->PostDelayedTask(FROM_HERE,
+                                base::Bind(&TestTask, &run_times, clock_.get()),
+                                base::TimeDelta::FromMilliseconds(900.0));
+
+  mock_task_runner_->RunUntilIdle();
+
+  // Advance realtime.
+  clock_->Advance(base::TimeDelta::FromMilliseconds(250));
+
+  // Post a task that due to real time + delay must run in the third aligned
+  // time period.
+  timer_queue_->PostDelayedTask(FROM_HERE,
+                                base::Bind(&TestTask, &run_times, clock_.get()),
+                                base::TimeDelta::FromMilliseconds(900.0));
+
+  mock_task_runner_->RunUntilIdle();
+
+  EXPECT_THAT(
+      run_times,
+      ElementsAre(
+          base::TimeTicks() + base::TimeDelta::FromMilliseconds(1000.0),
+          base::TimeTicks() + base::TimeDelta::FromMilliseconds(3000.0)));
+}
+
 }  // namespace scheduler