GetTimeToCallback() returns estimated time to callback.

base/timer/timer_unittest.cc

Index: base/timer/timer_unittest.cc
diff --git a/base/timer/timer_unittest.cc b/base/timer/timer_unittest.cc
index 7c3c1079d72f54be9585287c4ace5473c9c7b5f2..58029bef801e6d2b25b82b511558c381b9fb6ad9 100644
--- a/base/timer/timer_unittest.cc
+++ b/base/timer/timer_unittest.cc
@@ -623,6 +623,75 @@ TEST(TimerTest, RetainNonRepeatIsRunning) {
   EXPECT_TRUE(timer.IsRunning());
 }
 
+//-----------------------------------------------------------------------------
+
+TEST(TimerTest, RetainRepeatGetTimeToCallback) {
+  scoped_refptr<TestMockTimeTaskRunner> task_runner(
+      new TestMockTimeTaskRunner(Time::Now(), TimeTicks::Now()));
+  std::unique_ptr<TickClock> tick_clock(task_runner->GetMockTickClock());
+  MessageLoop message_loop;
+  message_loop.SetTaskRunner(task_runner);
+  Timer timer(true, true, tick_clock.get());
+  timer.Start(FROM_HERE, TimeDelta::FromSeconds(2), Bind(&TimerTestCallback));
+  EXPECT_EQ(TimeDelta::FromSeconds(2), timer.GetTimeToCallback());
+  task_runner->FastForwardBy(TimeDelta::FromSeconds(2));
+  EXPECT_EQ(TimeDelta::FromSeconds(2), timer.GetTimeToCallback());
+  timer.Stop();
+  task_runner->FastForwardBy(TimeDelta::FromSeconds(2));
+  EXPECT_EQ(TimeDelta::FromSeconds(0), timer.GetTimeToCallback());
+  task_runner->FastForwardBy(TimeDelta::FromSeconds(2));
+  EXPECT_EQ(TimeDelta::FromSeconds(-2), timer.GetTimeToCallback());
+}
+
+TEST(TimerTest, RetainNonRepeatGetTimeToCallback) {
+  scoped_refptr<TestMockTimeTaskRunner> task_runner(
+      new TestMockTimeTaskRunner(Time::Now(), TimeTicks::Now()));
+  std::unique_ptr<TickClock> tick_clock(task_runner->GetMockTickClock());
+  MessageLoop message_loop;
+  message_loop.SetTaskRunner(task_runner);
+  Timer timer(true, false, tick_clock.get());
+  timer.Start(FROM_HERE, TimeDelta::FromSeconds(2), Bind(&TimerTestCallback));
+  EXPECT_EQ(TimeDelta::FromSeconds(2), timer.GetTimeToCallback());
+  task_runner->FastForwardBy(TimeDelta::FromSeconds(3));
+  EXPECT_EQ(TimeDelta::FromSeconds(-1), timer.GetTimeToCallback());
+}
+
+TEST(TimerTest, OneShotTimerWithTickClockGetTimeToCallback) {
+  scoped_refptr<TestMockTimeTaskRunner> task_runner(
+      new TestMockTimeTaskRunner(Time::Now(), TimeTicks::Now()));
+  std::unique_ptr<TickClock> tick_clock(task_runner->GetMockTickClock());
+  MessageLoop message_loop;
+  message_loop.SetTaskRunner(task_runner);
+  Receiver receiver;
+  OneShotTimer timer(tick_clock.get());
+  EXPECT_EQ(TimeDelta::Max(), timer.GetTimeToCallback());
+  timer.Start(FROM_HERE, TimeDelta::FromSeconds(2),
+              Bind(&Receiver::OnCalled, Unretained(&receiver)));
+  EXPECT_EQ(TimeDelta::FromSeconds(2), timer.GetTimeToCallback());
+  task_runner->FastForwardBy(TimeDelta::FromSeconds(1));
+  EXPECT_EQ(TimeDelta::FromSeconds(1), timer.GetTimeToCallback());
+  task_runner->FastForwardBy(TimeDelta::FromSeconds(1));
+  EXPECT_TRUE(receiver.WasCalled());
+  EXPECT_EQ(TimeDelta::Max(), timer.GetTimeToCallback());
+}
+
+TEST(TimerTest, RepeatingTimerWithTickClockTimeToCallback) {
+  scoped_refptr<TestMockTimeTaskRunner> task_runner(
+      new TestMockTimeTaskRunner(Time::Now(), TimeTicks::Now()));
+  std::unique_ptr<TickClock> tick_clock(task_runner->GetMockTickClock());
+  MessageLoop message_loop;
+  message_loop.SetTaskRunner(task_runner);
+  Receiver receiver;
+  RepeatingTimer timer(tick_clock.get());
+  timer.Start(FROM_HERE, TimeDelta::FromSeconds(2),
+              Bind(&Receiver::OnCalled, Unretained(&receiver)));
+  EXPECT_EQ(TimeDelta::FromSeconds(2), timer.GetTimeToCallback());
+  task_runner->FastForwardBy(TimeDelta::FromSeconds(1));
+  EXPECT_EQ(TimeDelta::FromSeconds(1), timer.GetTimeToCallback());
+  task_runner->FastForwardBy(TimeDelta::FromSeconds(1));
+  EXPECT_EQ(TimeDelta::FromSeconds(2), timer.GetTimeToCallback());
+}
+
 namespace {
 
 bool g_callback_happened1 = false;