[cherrypick] Fix computation of runtime for throttled tasks

components/scheduler/renderer/throttling_helper_unittest.cc

 // 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.
 
 #include "components/scheduler/renderer/throttling_helper.h"
 
 #include <stddef.h>
 
 #include "base/callback.h"
 #include "base/macros.h"
@@ skipping 258 matching lines @@
 
   EXPECT_EQ(2u, task_count);  // There are two since the cancelled task runs in
   // the same DoWork batch.
 
   EXPECT_THAT(
       run_times,
       ElementsAre(base::TimeTicks() + base::TimeDelta::FromSeconds(6),
                   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