cc: Chromify TimeSource, DelayBasedTimeSource and test

cc/scheduler/delay_based_time_source_unittest.cc

Index: cc/scheduler/delay_based_time_source_unittest.cc
diff --git a/cc/scheduler/delay_based_time_source_unittest.cc b/cc/scheduler/delay_based_time_source_unittest.cc
index de4e11ec50284c8b7170b5984f7aa34a6371c67f..8343cce0feb3b1d0efee4aa24cdfc8e8a27b762f 100644
--- a/cc/scheduler/delay_based_time_source_unittest.cc
+++ b/cc/scheduler/delay_based_time_source_unittest.cc
@@ -11,363 +11,370 @@
 namespace cc {
 namespace {
 
-base::TimeDelta interval()
-{
-    return base::TimeDelta::FromMicroseconds(base::Time::kMicrosecondsPerSecond / 60);
+base::TimeDelta Interval() {
+  return base::TimeDelta::FromMicroseconds(base::Time::kMicrosecondsPerSecond /
+                                           60);
 }
 
-TEST(DelayBasedTimeSourceTest, TaskPostedAndTickCalled)
-{
-    FakeThread thread;
-    FakeTimeSourceClient client;
-    scoped_refptr<FakeDelayBasedTimeSource> timer = FakeDelayBasedTimeSource::create(interval(), &thread);
-    timer->setClient(&client);
-
-    timer->setActive(true);
-    EXPECT_TRUE(timer->active());
-    EXPECT_TRUE(thread.hasPendingTask());
-
-    timer->setNow(timer->now() + base::TimeDelta::FromMilliseconds(16));
-    thread.runPendingTask();
-    EXPECT_TRUE(timer->active());
-    EXPECT_TRUE(client.tickCalled());
+TEST(DelayBasedTimeSourceTest, TaskPostedAndTickCalled) {
+  FakeThread thread;
+  FakeTimeSourceClient client;
+  scoped_refptr<FakeDelayBasedTimeSource> timer =
+      FakeDelayBasedTimeSource::create(Interval(), &thread);
+  timer->SetClient(&client);
+
+  timer->SetActive(true);
+  EXPECT_TRUE(timer->Active());
+  EXPECT_TRUE(thread.hasPendingTask());
+
+  timer->setNow(timer->Now() + base::TimeDelta::FromMilliseconds(16));
+  thread.runPendingTask();
+  EXPECT_TRUE(timer->Active());
+  EXPECT_TRUE(client.tickCalled());
 }
 
-TEST(DelayBasedTimeSource, TickNotCalledWithTaskPosted)
-{
-    FakeThread thread;
-    FakeTimeSourceClient client;
-    scoped_refptr<FakeDelayBasedTimeSource> timer = FakeDelayBasedTimeSource::create(interval(), &thread);
-    timer->setClient(&client);
-    timer->setActive(true);
-    EXPECT_TRUE(thread.hasPendingTask());
-    timer->setActive(false);
-    thread.runPendingTask();
-    EXPECT_FALSE(client.tickCalled());
+TEST(DelayBasedTimeSource, TickNotCalledWithTaskPosted) {
+  FakeThread thread;
+  FakeTimeSourceClient client;
+  scoped_refptr<FakeDelayBasedTimeSource> timer =
+      FakeDelayBasedTimeSource::create(Interval(), &thread);
+  timer->SetClient(&client);
+  timer->SetActive(true);
+  EXPECT_TRUE(thread.hasPendingTask());
+  timer->SetActive(false);
+  thread.runPendingTask();
+  EXPECT_FALSE(client.tickCalled());
 }
 
-TEST(DelayBasedTimeSource, StartTwiceEnqueuesOneTask)
-{
-    FakeThread thread;
-    FakeTimeSourceClient client;
-    scoped_refptr<FakeDelayBasedTimeSource> timer = FakeDelayBasedTimeSource::create(interval(), &thread);
-    timer->setClient(&client);
-    timer->setActive(true);
-    EXPECT_TRUE(thread.hasPendingTask());
-    thread.reset();
-    timer->setActive(true);
-    EXPECT_FALSE(thread.hasPendingTask());
+TEST(DelayBasedTimeSource, StartTwiceEnqueuesOneTask) {
+  FakeThread thread;
+  FakeTimeSourceClient client;
+  scoped_refptr<FakeDelayBasedTimeSource> timer =
+      FakeDelayBasedTimeSource::create(Interval(), &thread);
+  timer->SetClient(&client);
+  timer->SetActive(true);
+  EXPECT_TRUE(thread.hasPendingTask());
+  thread.reset();
+  timer->SetActive(true);
+  EXPECT_FALSE(thread.hasPendingTask());
 }
 
-TEST(DelayBasedTimeSource, StartWhenRunningDoesntTick)
-{
-    FakeThread thread;
-    FakeTimeSourceClient client;
-    scoped_refptr<FakeDelayBasedTimeSource> timer = FakeDelayBasedTimeSource::create(interval(), &thread);
-    timer->setClient(&client);
-    timer->setActive(true);
-    thread.runPendingTask();
-    thread.reset();
-    timer->setActive(true);
-    EXPECT_FALSE(thread.hasPendingTask());
+TEST(DelayBasedTimeSource, StartWhenRunningDoesntTick) {
+  FakeThread thread;
+  FakeTimeSourceClient client;
+  scoped_refptr<FakeDelayBasedTimeSource> timer =
+      FakeDelayBasedTimeSource::create(Interval(), &thread);
+  timer->SetClient(&client);
+  timer->SetActive(true);
+  thread.runPendingTask();
+  thread.reset();
+  timer->SetActive(true);
+  EXPECT_FALSE(thread.hasPendingTask());
 }
 
 // At 60Hz, when the tick returns at exactly the requested next time, make sure
 // a 16ms next delay is posted.
-TEST(DelayBasedTimeSource, NextDelaySaneWhenExactlyOnRequestedTime)
-{
-    FakeThread thread;
-    FakeTimeSourceClient client;
-    scoped_refptr<FakeDelayBasedTimeSource> timer = FakeDelayBasedTimeSource::create(interval(), &thread);
-    timer->setClient(&client);
-    timer->setActive(true);
-    // Run the first task, as that activates the timer and picks up a timebase.
-    thread.runPendingTask();
-
-    EXPECT_EQ(16, thread.pendingDelayMs());
-
-    timer->setNow(timer->now() + interval());
-    thread.runPendingTask();
-
-    EXPECT_EQ(16, thread.pendingDelayMs());
+TEST(DelayBasedTimeSource, NextDelaySaneWhenExactlyOnRequestedTime) {
+  FakeThread thread;
+  FakeTimeSourceClient client;
+  scoped_refptr<FakeDelayBasedTimeSource> timer =
+      FakeDelayBasedTimeSource::create(Interval(), &thread);
+  timer->SetClient(&client);
+  timer->SetActive(true);
+  // Run the first task, as that activates the timer and picks up a timebase.
+  thread.runPendingTask();
+
+  EXPECT_EQ(16, thread.pendingDelayMs());
+
+  timer->setNow(timer->Now() + Interval());
+  thread.runPendingTask();
+
+  EXPECT_EQ(16, thread.pendingDelayMs());
 }
 
-// At 60Hz, when the tick returns at slightly after the requested next time, make sure
-// a 16ms next delay is posted.
-TEST(DelayBasedTimeSource, NextDelaySaneWhenSlightlyAfterRequestedTime)
-{
-    FakeThread thread;
-    FakeTimeSourceClient client;
-    scoped_refptr<FakeDelayBasedTimeSource> timer = FakeDelayBasedTimeSource::create(interval(), &thread);
-    timer->setClient(&client);
-    timer->setActive(true);
-    // Run the first task, as that activates the timer and picks up a timebase.
-    thread.runPendingTask();
-
-    EXPECT_EQ(16, thread.pendingDelayMs());
-
-    timer->setNow(timer->now() + interval() + base::TimeDelta::FromMicroseconds(1));
-    thread.runPendingTask();
-
-    EXPECT_EQ(16, thread.pendingDelayMs());
+// At 60Hz, when the tick returns at slightly after the requested next time,
+// make sure a 16ms next delay is posted.
+TEST(DelayBasedTimeSource, NextDelaySaneWhenSlightlyAfterRequestedTime) {
+  FakeThread thread;
+  FakeTimeSourceClient client;
+  scoped_refptr<FakeDelayBasedTimeSource> timer =
+      FakeDelayBasedTimeSource::create(Interval(), &thread);
+  timer->SetClient(&client);
+  timer->SetActive(true);
+  // Run the first task, as that activates the timer and picks up a timebase.
+  thread.runPendingTask();
+
+  EXPECT_EQ(16, thread.pendingDelayMs());
+
+  timer->setNow(timer->Now() + Interval() +
+                base::TimeDelta::FromMicroseconds(1));
+  thread.runPendingTask();
+
+  EXPECT_EQ(16, thread.pendingDelayMs());
 }
 
-// At 60Hz, when the tick returns at exactly 2*interval after the requested next time, make sure
-// a 16ms next delay is posted.
-TEST(DelayBasedTimeSource, NextDelaySaneWhenExactlyTwiceAfterRequestedTime)
-{
-    FakeThread thread;
-    FakeTimeSourceClient client;
-    scoped_refptr<FakeDelayBasedTimeSource> timer = FakeDelayBasedTimeSource::create(interval(), &thread);
-    timer->setClient(&client);
-    timer->setActive(true);
-    // Run the first task, as that activates the timer and picks up a timebase.
-    thread.runPendingTask();
+// At 60Hz, when the tick returns at exactly 2*interval after the requested next
+// time, make sure a 16ms next delay is posted.
+TEST(DelayBasedTimeSource, NextDelaySaneWhenExactlyTwiceAfterRequestedTime) {
+  FakeThread thread;
+  FakeTimeSourceClient client;
+  scoped_refptr<FakeDelayBasedTimeSource> timer =
+      FakeDelayBasedTimeSource::create(Interval(), &thread);
+  timer->SetClient(&client);
+  timer->SetActive(true);
+  // Run the first task, as that activates the timer and picks up a timebase.
+  thread.runPendingTask();
 
-    EXPECT_EQ(16, thread.pendingDelayMs());
+  EXPECT_EQ(16, thread.pendingDelayMs());
 
-    timer->setNow(timer->now() + 2 * interval());
-    thread.runPendingTask();
+  timer->setNow(timer->Now() + 2 * Interval());
+  thread.runPendingTask();
 
-    EXPECT_EQ(16, thread.pendingDelayMs());
+  EXPECT_EQ(16, thread.pendingDelayMs());
 }
 
-// At 60Hz, when the tick returns at 2*interval and a bit after the requested next time, make sure
-// a 16ms next delay is posted.
-TEST(DelayBasedTimeSource, NextDelaySaneWhenSlightlyAfterTwiceRequestedTime)
-{
-    FakeThread thread;
-    FakeTimeSourceClient client;
-    scoped_refptr<FakeDelayBasedTimeSource> timer = FakeDelayBasedTimeSource::create(interval(), &thread);
-    timer->setClient(&client);
-    timer->setActive(true);
-    // Run the first task, as that activates the timer and picks up a timebase.
-    thread.runPendingTask();
-
-    EXPECT_EQ(16, thread.pendingDelayMs());
-
-    timer->setNow(timer->now() + 2 * interval() + base::TimeDelta::FromMicroseconds(1));
-    thread.runPendingTask();
-
-    EXPECT_EQ(16, thread.pendingDelayMs());
+// At 60Hz, when the tick returns at 2*interval and a bit after the requested
+// next time, make sure a 16ms next delay is posted.
+TEST(DelayBasedTimeSource, NextDelaySaneWhenSlightlyAfterTwiceRequestedTime) {
+  FakeThread thread;
+  FakeTimeSourceClient client;
+  scoped_refptr<FakeDelayBasedTimeSource> timer =
+      FakeDelayBasedTimeSource::create(Interval(), &thread);
+  timer->SetClient(&client);
+  timer->SetActive(true);
+  // Run the first task, as that activates the timer and picks up a timebase.
+  thread.runPendingTask();
+
+  EXPECT_EQ(16, thread.pendingDelayMs());
+
+  timer->setNow(timer->Now() + 2 * Interval() +
+                base::TimeDelta::FromMicroseconds(1));
+  thread.runPendingTask();
+
+  EXPECT_EQ(16, thread.pendingDelayMs());
 }
 
 // At 60Hz, when the tick returns halfway to the next frame time, make sure
 // a correct next delay value is posted.
-TEST(DelayBasedTimeSource, NextDelaySaneWhenHalfAfterRequestedTime)
-{
-    FakeThread thread;
-    FakeTimeSourceClient client;
-    scoped_refptr<FakeDelayBasedTimeSource> timer = FakeDelayBasedTimeSource::create(interval(), &thread);
-    timer->setClient(&client);
-    timer->setActive(true);
-    // Run the first task, as that activates the timer and picks up a timebase.
-    thread.runPendingTask();
-
-    EXPECT_EQ(16, thread.pendingDelayMs());
-
-    timer->setNow(timer->now() + interval() + base::TimeDelta::FromMilliseconds(8));
-    thread.runPendingTask();
-
-    EXPECT_EQ(8, thread.pendingDelayMs());
+TEST(DelayBasedTimeSource, NextDelaySaneWhenHalfAfterRequestedTime) {
+  FakeThread thread;
+  FakeTimeSourceClient client;
+  scoped_refptr<FakeDelayBasedTimeSource> timer =
+      FakeDelayBasedTimeSource::create(Interval(), &thread);
+  timer->SetClient(&client);
+  timer->SetActive(true);
+  // Run the first task, as that activates the timer and picks up a timebase.
+  thread.runPendingTask();
+
+  EXPECT_EQ(16, thread.pendingDelayMs());
+
+  timer->setNow(timer->Now() + Interval() +
+                base::TimeDelta::FromMilliseconds(8));
+  thread.runPendingTask();
+
+  EXPECT_EQ(8, thread.pendingDelayMs());
 }
 
 // If the timebase and interval are updated with a jittery source, we want to
 // make sure we do not double tick.
-TEST(DelayBasedTimeSource, SaneHandlingOfJitteryTimebase)
-{
-    FakeThread thread;
-    FakeTimeSourceClient client;
-    scoped_refptr<FakeDelayBasedTimeSource> timer = FakeDelayBasedTimeSource::create(interval(), &thread);
-    timer->setClient(&client);
-    timer->setActive(true);
-    // Run the first task, as that activates the timer and picks up a timebase.
-    thread.runPendingTask();
+TEST(DelayBasedTimeSource, SaneHandlingOfJitteryTimebase) {
+  FakeThread thread;
+  FakeTimeSourceClient client;
+  scoped_refptr<FakeDelayBasedTimeSource> timer =
+      FakeDelayBasedTimeSource::create(Interval(), &thread);
+  timer->SetClient(&client);
+  timer->SetActive(true);
+  // Run the first task, as that activates the timer and picks up a timebase.
+  thread.runPendingTask();
+
+  EXPECT_EQ(16, thread.pendingDelayMs());
+
+  // Jitter timebase ~1ms late
+  timer->setNow(timer->Now() + Interval());
+  timer->SetTimebaseAndInterval(
+      timer->Now() + base::TimeDelta::FromMilliseconds(1), Interval());
+  thread.runPendingTask();
+
+  // Without double tick prevention, pendingDelayMs would be 1.
+  EXPECT_EQ(17, thread.pendingDelayMs());
+
+  // Jitter timebase ~1ms early
+  timer->setNow(timer->Now() + Interval());
+  timer->SetTimebaseAndInterval(
+      timer->Now() - base::TimeDelta::FromMilliseconds(1), Interval());
+  thread.runPendingTask();
+
+  EXPECT_EQ(15, thread.pendingDelayMs());
+}
 
-    EXPECT_EQ(16, thread.pendingDelayMs());
+TEST(DelayBasedTimeSource, HandlesSignificantTimebaseChangesImmediately) {
+  FakeThread thread;
+  FakeTimeSourceClient client;
+  scoped_refptr<FakeDelayBasedTimeSource> timer =
+      FakeDelayBasedTimeSource::create(Interval(), &thread);
+  timer->SetClient(&client);
+  timer->SetActive(true);
+  // Run the first task, as that activates the timer and picks up a timebase.
+  thread.runPendingTask();
 
-    // Jitter timebase ~1ms late
-    timer->setNow(timer->now() + interval());
-    timer->setTimebaseAndInterval(timer->now() + base::TimeDelta::FromMilliseconds(1), interval());
-    thread.runPendingTask();
+  EXPECT_EQ(16, thread.pendingDelayMs());
 
-    // Without double tick prevention, pendingDelayMs would be 1.
-    EXPECT_EQ(17, thread.pendingDelayMs());
+  // Tick, then shift timebase by +7ms.
+  timer->setNow(timer->Now() + Interval());
+  thread.runPendingTask();
 
-    // Jitter timebase ~1ms early
-    timer->setNow(timer->now() + interval());
-    timer->setTimebaseAndInterval(timer->now() - base::TimeDelta::FromMilliseconds(1), interval());
-    thread.runPendingTask();
+  EXPECT_EQ(16, thread.pendingDelayMs());
 
-    EXPECT_EQ(15, thread.pendingDelayMs());
-}
+  client.reset();
+  thread.runPendingTaskOnOverwrite(true);
+  base::TimeDelta jitter = base::TimeDelta::FromMilliseconds(7) +
+                           base::TimeDelta::FromMicroseconds(1);
+  timer->SetTimebaseAndInterval(timer->Now() + jitter, Interval());
+  thread.runPendingTaskOnOverwrite(false);
 
-TEST(DelayBasedTimeSource, HandlesSignificantTimebaseChangesImmediately)
-{
-    FakeThread thread;
-    FakeTimeSourceClient client;
-    scoped_refptr<FakeDelayBasedTimeSource> timer = FakeDelayBasedTimeSource::create(interval(), &thread);
-    timer->setClient(&client);
-    timer->setActive(true);
-    // Run the first task, as that activates the timer and picks up a timebase.
-    thread.runPendingTask();
+  EXPECT_FALSE(client.tickCalled());  // Make sure pending tasks were canceled.
+  EXPECT_EQ(7, thread.pendingDelayMs());
 
-    EXPECT_EQ(16, thread.pendingDelayMs());
+  // Tick, then shift timebase by -7ms.
+  timer->setNow(timer->Now() + jitter);
+  thread.runPendingTask();
 
-    // Tick, then shift timebase by +7ms.
-    timer->setNow(timer->now() + interval());
-    thread.runPendingTask();
+  EXPECT_EQ(16, thread.pendingDelayMs());
 
-    EXPECT_EQ(16, thread.pendingDelayMs());
+  client.reset();
+  thread.runPendingTaskOnOverwrite(true);
+  timer->SetTimebaseAndInterval(base::TimeTicks() + Interval(), Interval());
+  thread.runPendingTaskOnOverwrite(false);
 
-    client.reset();
-    thread.runPendingTaskOnOverwrite(true);
-    base::TimeDelta jitter = base::TimeDelta::FromMilliseconds(7) + base::TimeDelta::FromMicroseconds(1);
-    timer->setTimebaseAndInterval(timer->now() + jitter, interval());
-    thread.runPendingTaskOnOverwrite(false);
+  EXPECT_FALSE(client.tickCalled());  // Make sure pending tasks were canceled.
+  EXPECT_EQ(16 - 7, thread.pendingDelayMs());
+}
 
-    EXPECT_FALSE(client.tickCalled()); // Make sure pending tasks were canceled.
-    EXPECT_EQ(7, thread.pendingDelayMs());
+TEST(DelayBasedTimeSource, HanldlesSignificantIntervalChangesImmediately) {
+  FakeThread thread;
+  FakeTimeSourceClient client;
+  scoped_refptr<FakeDelayBasedTimeSource> timer =
+      FakeDelayBasedTimeSource::create(Interval(), &thread);
+  timer->SetClient(&client);
+  timer->SetActive(true);
+  // Run the first task, as that activates the timer and picks up a timebase.
+  thread.runPendingTask();
 
-    // Tick, then shift timebase by -7ms.
-    timer->setNow(timer->now() + jitter);
-    thread.runPendingTask();
+  EXPECT_EQ(16, thread.pendingDelayMs());
 
-    EXPECT_EQ(16, thread.pendingDelayMs());
+  // Tick, then double the interval.
+  timer->setNow(timer->Now() + Interval());
+  thread.runPendingTask();
 
-    client.reset();
-    thread.runPendingTaskOnOverwrite(true);
-    timer->setTimebaseAndInterval(base::TimeTicks() + interval(), interval());
-    thread.runPendingTaskOnOverwrite(false);
+  EXPECT_EQ(16, thread.pendingDelayMs());
 
-    EXPECT_FALSE(client.tickCalled()); // Make sure pending tasks were canceled.
-    EXPECT_EQ(16-7, thread.pendingDelayMs());
-}
-
-TEST(DelayBasedTimeSource, HanldlesSignificantIntervalChangesImmediately)
-{
-    FakeThread thread;
-    FakeTimeSourceClient client;
-    scoped_refptr<FakeDelayBasedTimeSource> timer = FakeDelayBasedTimeSource::create(interval(), &thread);
-    timer->setClient(&client);
-    timer->setActive(true);
-    // Run the first task, as that activates the timer and picks up a timebase.
-    thread.runPendingTask();
+  client.reset();
+  thread.runPendingTaskOnOverwrite(true);
+  timer->SetTimebaseAndInterval(base::TimeTicks() + Interval(), Interval() * 2);
+  thread.runPendingTaskOnOverwrite(false);
 
-    EXPECT_EQ(16, thread.pendingDelayMs());
+  EXPECT_FALSE(client.tickCalled());  // Make sure pending tasks were canceled.
+  EXPECT_EQ(33, thread.pendingDelayMs());
 
-    // Tick, then double the interval.
-    timer->setNow(timer->now() + interval());
-    thread.runPendingTask();
+  // Tick, then halve the interval.
+  timer->setNow(timer->Now() + Interval() * 2);
+  thread.runPendingTask();
 
-    EXPECT_EQ(16, thread.pendingDelayMs());
+  EXPECT_EQ(33, thread.pendingDelayMs());
 
-    client.reset();
-    thread.runPendingTaskOnOverwrite(true);
-    timer->setTimebaseAndInterval(base::TimeTicks() + interval(), interval() * 2);
-    thread.runPendingTaskOnOverwrite(false);
+  client.reset();
+  thread.runPendingTaskOnOverwrite(true);
+  timer->SetTimebaseAndInterval(base::TimeTicks() + Interval() * 3, Interval());
+  thread.runPendingTaskOnOverwrite(false);
 
-    EXPECT_FALSE(client.tickCalled()); // Make sure pending tasks were canceled.
-    EXPECT_EQ(33, thread.pendingDelayMs());
+  EXPECT_FALSE(client.tickCalled());  // Make sure pending tasks were canceled.
+  EXPECT_EQ(16, thread.pendingDelayMs());
+}
 
-    // Tick, then halve the interval.
-    timer->setNow(timer->now() + interval() * 2);
-    thread.runPendingTask();
+TEST(DelayBasedTimeSourceTest, AchievesTargetRateWithNoNoise) {
+  int num_iterations = 10;
 
-    EXPECT_EQ(33, thread.pendingDelayMs());
+  FakeThread thread;
+  FakeTimeSourceClient client;
+  scoped_refptr<FakeDelayBasedTimeSource> timer =
+      FakeDelayBasedTimeSource::create(Interval(), &thread);
+  timer->SetClient(&client);
+  timer->SetActive(true);
 
-    client.reset();
-    thread.runPendingTaskOnOverwrite(true);
-    timer->setTimebaseAndInterval(base::TimeTicks() + interval() * 3, interval());
-    thread.runPendingTaskOnOverwrite(false);
+  double total_frame_time = 0.0;
+  for (int i = 0; i < num_iterations; ++i) {
+    long long delay_ms = thread.pendingDelayMs();
 
-    EXPECT_FALSE(client.tickCalled()); // Make sure pending tasks were canceled.
-    EXPECT_EQ(16, thread.pendingDelayMs());
-}
+    // accumulate the "delay"
+    total_frame_time += delay_ms / 1000.0;
 
-TEST(DelayBasedTimeSourceTest, AchievesTargetRateWithNoNoise)
-{
-    int numIterations = 10;
-
-    FakeThread thread;
-    FakeTimeSourceClient client;
-    scoped_refptr<FakeDelayBasedTimeSource> timer = FakeDelayBasedTimeSource::create(interval(), &thread);
-    timer->setClient(&client);
-    timer->setActive(true);
-
-    double totalFrameTime = 0;
-    for (int i = 0; i < numIterations; ++i) {
-        long long delayMs = thread.pendingDelayMs();
-
-        // accumulate the "delay"
-        totalFrameTime += delayMs / 1000.0;
-
-        // Run the callback exactly when asked
-        timer->setNow(timer->now() + base::TimeDelta::FromMilliseconds(delayMs));
-        thread.runPendingTask();
-    }
-    double averageInterval = totalFrameTime / static_cast<double>(numIterations);
-    EXPECT_NEAR(1.0 / 60.0, averageInterval, 0.1);
+    // Run the callback exactly when asked
+    timer->setNow(timer->Now() + base::TimeDelta::FromMilliseconds(delay_ms));
+    thread.runPendingTask();
+  }
+  double average_interval =
+      total_frame_time / static_cast<double>(num_iterations);
+  EXPECT_NEAR(1.0 / 60.0, average_interval, 0.1);
 }
 
-TEST(DelayBasedTimeSource, TestDeactivateWhilePending)
-{
-    FakeThread thread;
-    FakeTimeSourceClient client;
-    scoped_refptr<FakeDelayBasedTimeSource> timer = FakeDelayBasedTimeSource::create(interval(), &thread);
-    timer->setClient(&client);
-    timer->setActive(true); // Should post a task.
-    timer->setActive(false);
-    timer = NULL;
-    thread.runPendingTask(); // Should run the posted task without crashing.
+TEST(DelayBasedTimeSource, TestDeactivateWhilePending) {
+  FakeThread thread;
+  FakeTimeSourceClient client;
+  scoped_refptr<FakeDelayBasedTimeSource> timer =
+      FakeDelayBasedTimeSource::create(Interval(), &thread);
+  timer->SetClient(&client);
+  timer->SetActive(true);  // Should post a task.
+  timer->SetActive(false);
+  timer = NULL;
+  thread.runPendingTask();  // Should run the posted task without crashing.
 }
 
-TEST(DelayBasedTimeSource, TestDeactivateAndReactivateBeforeNextTickTime)
-{
-    FakeThread thread;
-    FakeTimeSourceClient client;
-    scoped_refptr<FakeDelayBasedTimeSource> timer = FakeDelayBasedTimeSource::create(interval(), &thread);
-    timer->setClient(&client);
+TEST(DelayBasedTimeSource, TestDeactivateAndReactivateBeforeNextTickTime) {
+  FakeThread thread;
+  FakeTimeSourceClient client;
+  scoped_refptr<FakeDelayBasedTimeSource> timer =
+      FakeDelayBasedTimeSource::create(Interval(), &thread);
+  timer->SetClient(&client);
 
-    // Should run the activate task, and pick up a new timebase.
-    timer->setActive(true);
-    thread.runPendingTask();
+  // Should run the activate task, and pick up a new timebase.
+  timer->SetActive(true);
+  thread.runPendingTask();
 
-    // Stop the timer
-    timer->setActive(false);
+  // Stop the timer
+  timer->SetActive(false);
 
-    // Task will be pending anyway, run it
-    thread.runPendingTask();
+  // Task will be pending anyway, run it
+  thread.runPendingTask();
 
-    // Start the timer again, but before the next tick time the timer previously
-    // planned on using. That same tick time should still be targeted.
-    timer->setNow(timer->now() + base::TimeDelta::FromMilliseconds(4));
-    timer->setActive(true);
-    EXPECT_EQ(12, thread.pendingDelayMs());
+  // Start the timer again, but before the next tick time the timer previously
+  // planned on using. That same tick time should still be targeted.
+  timer->setNow(timer->Now() + base::TimeDelta::FromMilliseconds(4));
+  timer->SetActive(true);
+  EXPECT_EQ(12, thread.pendingDelayMs());
 }
 
-TEST(DelayBasedTimeSource, TestDeactivateAndReactivateAfterNextTickTime)
-{
-    FakeThread thread;
-    FakeTimeSourceClient client;
-    scoped_refptr<FakeDelayBasedTimeSource> timer = FakeDelayBasedTimeSource::create(interval(), &thread);
-    timer->setClient(&client);
+TEST(DelayBasedTimeSource, TestDeactivateAndReactivateAfterNextTickTime) {
+  FakeThread thread;
+  FakeTimeSourceClient client;
+  scoped_refptr<FakeDelayBasedTimeSource> timer =
+      FakeDelayBasedTimeSource::create(Interval(), &thread);
+  timer->SetClient(&client);
 
-    // Should run the activate task, and pick up a new timebase.
-    timer->setActive(true);
-    thread.runPendingTask();
+  // Should run the activate task, and pick up a new timebase.
+  timer->SetActive(true);
+  thread.runPendingTask();
 
-    // Stop the timer
-    timer->setActive(false);
+  // Stop the timer.
+  timer->SetActive(false);
 
-    // Task will be pending anyway, run it
-    thread.runPendingTask();
+  // Task will be pending anyway, run it.
+  thread.runPendingTask();
 
-    // Start the timer again, but before the next tick time the timer previously
-    // planned on using. That same tick time should still be targeted.
-    timer->setNow(timer->now() + base::TimeDelta::FromMilliseconds(20));
-    timer->setActive(true);
-    EXPECT_EQ(13, thread.pendingDelayMs());
+  // Start the timer again, but before the next tick time the timer previously
+  // planned on using. That same tick time should still be targeted.
+  timer->setNow(timer->Now() + base::TimeDelta::FromMilliseconds(20));
+  timer->SetActive(true);
+  EXPECT_EQ(13, thread.pendingDelayMs());
 }
 
 }  // namespace