cc/scheduler/delay_based_time_source_unittest.cc

   1 // Copyright 2011 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "cc/scheduler/delay_based_time_source.h"
   6
   7 #include "base/basictypes.h"
   8 #include "base/test/test_simple_task_runner.h"
   9 #include "cc/test/scheduler_test_common.h"
  10 #include "testing/gtest/include/gtest/gtest.h"
  11
  12 namespace cc {
  13 namespace {
  14
  15 base::TimeDelta Interval() {
  16   return base::TimeDelta::FromMicroseconds(base::Time::kMicrosecondsPerSecond /
  17                                            60);
  18 }
  19
  20 TEST(DelayBasedTimeSourceTest, TaskPostedAndTickCalled) {
  21   scoped_refptr<base::TestSimpleTaskRunner> task_runner =
  22       new base::TestSimpleTaskRunner;
  23   FakeTimeSourceClient client;
  24   scoped_refptr<FakeDelayBasedTimeSource> timer =
  25       FakeDelayBasedTimeSource::Create(Interval(), task_runner.get());
  26   timer->SetClient(&client);
  27
  28   timer->SetActive(true);
  29   EXPECT_TRUE(timer->Active());
  30   EXPECT_TRUE(task_runner->HasPendingTask());
  31
  32   timer->SetNow(timer->Now() + base::TimeDelta::FromMilliseconds(16));
  33   task_runner->RunPendingTasks();
  34   EXPECT_TRUE(timer->Active());
  35   EXPECT_TRUE(client.TickCalled());
  36 }
  37
  38 TEST(DelayBasedTimeSourceTest, TickNotCalledWithTaskPosted) {
  39   scoped_refptr<base::TestSimpleTaskRunner> task_runner =
  40       new base::TestSimpleTaskRunner;
  41   FakeTimeSourceClient client;
  42   scoped_refptr<FakeDelayBasedTimeSource> timer =
  43       FakeDelayBasedTimeSource::Create(Interval(), task_runner.get());
  44   timer->SetClient(&client);
  45   timer->SetActive(true);
  46   EXPECT_TRUE(task_runner->HasPendingTask());
  47   timer->SetActive(false);
  48   task_runner->RunPendingTasks();
  49   EXPECT_FALSE(client.TickCalled());
  50 }
  51
  52 TEST(DelayBasedTimeSourceTest, StartTwiceEnqueuesOneTask) {
  53   scoped_refptr<base::TestSimpleTaskRunner> task_runner =
  54       new base::TestSimpleTaskRunner;
  55   FakeTimeSourceClient client;
  56   scoped_refptr<FakeDelayBasedTimeSource> timer =
  57       FakeDelayBasedTimeSource::Create(Interval(), task_runner.get());
  58   timer->SetClient(&client);
  59   timer->SetActive(true);
  60   EXPECT_TRUE(task_runner->HasPendingTask());
  61   task_runner->ClearPendingTasks();
  62   timer->SetActive(true);
  63   EXPECT_FALSE(task_runner->HasPendingTask());
  64 }
  65
  66 TEST(DelayBasedTimeSourceTest, StartWhenRunningDoesntTick) {
  67   scoped_refptr<base::TestSimpleTaskRunner> task_runner =
  68       new base::TestSimpleTaskRunner;
  69   FakeTimeSourceClient client;
  70   scoped_refptr<FakeDelayBasedTimeSource> timer =
  71       FakeDelayBasedTimeSource::Create(Interval(), task_runner.get());
  72   timer->SetClient(&client);
  73   timer->SetActive(true);
  74   EXPECT_TRUE(task_runner->HasPendingTask());
  75   task_runner->RunPendingTasks();
  76   task_runner->ClearPendingTasks();
  77   timer->SetActive(true);
  78   EXPECT_FALSE(task_runner->HasPendingTask());
  79 }
  80
  81 // At 60Hz, when the tick returns at exactly the requested next time, make sure
  82 // a 16ms next delay is posted.
  83 TEST(DelayBasedTimeSourceTest, NextDelaySaneWhenExactlyOnRequestedTime) {
  84   scoped_refptr<base::TestSimpleTaskRunner> task_runner =
  85       new base::TestSimpleTaskRunner;
  86   FakeTimeSourceClient client;
  87   scoped_refptr<FakeDelayBasedTimeSource> timer =
  88       FakeDelayBasedTimeSource::Create(Interval(), task_runner.get());
  89   timer->SetClient(&client);
  90   timer->SetActive(true);
  91   // Run the first tick.
  92   task_runner->RunPendingTasks();
  93
  94   EXPECT_EQ(16, task_runner->NextPendingTaskDelay().InMilliseconds());
  95
  96   timer->SetNow(timer->Now() + Interval());
  97   task_runner->RunPendingTasks();
  98
  99   EXPECT_EQ(16, task_runner->NextPendingTaskDelay().InMilliseconds());
 100 }
 101
 102 // At 60Hz, when the tick returns at slightly after the requested next time,
 103 // make sure a 16ms next delay is posted.
 104 TEST(DelayBasedTimeSourceTest, NextDelaySaneWhenSlightlyAfterRequestedTime) {
 105   scoped_refptr<base::TestSimpleTaskRunner> task_runner =
 106       new base::TestSimpleTaskRunner;
 107   FakeTimeSourceClient client;
 108   scoped_refptr<FakeDelayBasedTimeSource> timer =
 109       FakeDelayBasedTimeSource::Create(Interval(), task_runner.get());
 110   timer->SetClient(&client);
 111   timer->SetActive(true);
 112   // Run the first tick.
 113   task_runner->RunPendingTasks();
 114
 115   EXPECT_EQ(16, task_runner->NextPendingTaskDelay().InMilliseconds());
 116
 117   timer->SetNow(timer->Now() + Interval() +
 118                 base::TimeDelta::FromMicroseconds(1));
 119   task_runner->RunPendingTasks();
 120
 121   EXPECT_EQ(16, task_runner->NextPendingTaskDelay().InMilliseconds());
 122 }
 123
 124 // At 60Hz, when the tick returns at exactly 2*interval after the requested next
 125 // time, make sure a 0ms next delay is posted.
 126 TEST(DelayBasedTimeSourceTest,
 127      NextDelaySaneWhenExactlyTwiceAfterRequestedTime) {
 128   scoped_refptr<base::TestSimpleTaskRunner> task_runner =
 129       new base::TestSimpleTaskRunner;
 130   FakeTimeSourceClient client;
 131   scoped_refptr<FakeDelayBasedTimeSource> timer =
 132       FakeDelayBasedTimeSource::Create(Interval(), task_runner.get());
 133   timer->SetClient(&client);
 134   timer->SetActive(true);
 135   // Run the first tick.
 136   task_runner->RunPendingTasks();
 137
 138   EXPECT_EQ(16, task_runner->NextPendingTaskDelay().InMilliseconds());
 139
 140   timer->SetNow(timer->Now() + 2 * Interval());
 141   task_runner->RunPendingTasks();
 142
 143   EXPECT_EQ(0, task_runner->NextPendingTaskDelay().InMilliseconds());
 144 }
 145
 146 // At 60Hz, when the tick returns at 2*interval and a bit after the requested
 147 // next time, make sure a 16ms next delay is posted.
 148 TEST(DelayBasedTimeSourceTest,
 149      NextDelaySaneWhenSlightlyAfterTwiceRequestedTime) {
 150   scoped_refptr<base::TestSimpleTaskRunner> task_runner =
 151       new base::TestSimpleTaskRunner;
 152   FakeTimeSourceClient client;
 153   scoped_refptr<FakeDelayBasedTimeSource> timer =
 154       FakeDelayBasedTimeSource::Create(Interval(), task_runner.get());
 155   timer->SetClient(&client);
 156   timer->SetActive(true);
 157   // Run the first tick.
 158   task_runner->RunPendingTasks();
 159
 160   EXPECT_EQ(16, task_runner->NextPendingTaskDelay().InMilliseconds());
 161
 162   timer->SetNow(timer->Now() + 2 * Interval() +
 163                 base::TimeDelta::FromMicroseconds(1));
 164   task_runner->RunPendingTasks();
 165
 166   EXPECT_EQ(16, task_runner->NextPendingTaskDelay().InMilliseconds());
 167 }
 168
 169 // At 60Hz, when the tick returns halfway to the next frame time, make sure
 170 // a correct next delay value is posted.
 171 TEST(DelayBasedTimeSourceTest, NextDelaySaneWhenHalfAfterRequestedTime) {
 172   scoped_refptr<base::TestSimpleTaskRunner> task_runner =
 173       new base::TestSimpleTaskRunner;
 174   FakeTimeSourceClient client;
 175   scoped_refptr<FakeDelayBasedTimeSource> timer =
 176       FakeDelayBasedTimeSource::Create(Interval(), task_runner.get());
 177   timer->SetClient(&client);
 178   timer->SetActive(true);
 179   // Run the first tick.
 180   task_runner->RunPendingTasks();
 181
 182   EXPECT_EQ(16, task_runner->NextPendingTaskDelay().InMilliseconds());
 183
 184   timer->SetNow(timer->Now() + Interval() +
 185                 base::TimeDelta::FromMilliseconds(8));
 186   task_runner->RunPendingTasks();
 187
 188   EXPECT_EQ(8, task_runner->NextPendingTaskDelay().InMilliseconds());
 189 }
 190
 191 // If the timebase and interval are updated with a jittery source, we want to
 192 // make sure we do not double tick.
 193 TEST(DelayBasedTimeSourceTest, SaneHandlingOfJitteryTimebase) {
 194   scoped_refptr<base::TestSimpleTaskRunner> task_runner =
 195       new base::TestSimpleTaskRunner;
 196   FakeTimeSourceClient client;
 197   scoped_refptr<FakeDelayBasedTimeSource> timer =
 198       FakeDelayBasedTimeSource::Create(Interval(), task_runner.get());
 199   timer->SetClient(&client);
 200   timer->SetActive(true);
 201   // Run the first tick.
 202   task_runner->RunPendingTasks();
 203
 204   EXPECT_EQ(16, task_runner->NextPendingTaskDelay().InMilliseconds());
 205
 206   // Jitter timebase ~1ms late
 207   timer->SetNow(timer->Now() + Interval());
 208   timer->SetTimebaseAndInterval(
 209       timer->Now() + base::TimeDelta::FromMilliseconds(1), Interval());
 210   task_runner->RunPendingTasks();
 211
 212   // Without double tick prevention, NextPendingTaskDelay would be 1.
 213   EXPECT_EQ(17, task_runner->NextPendingTaskDelay().InMilliseconds());
 214
 215   // Jitter timebase ~1ms early
 216   timer->SetNow(timer->Now() + Interval());
 217   timer->SetTimebaseAndInterval(
 218       timer->Now() - base::TimeDelta::FromMilliseconds(1), Interval());
 219   task_runner->RunPendingTasks();
 220
 221   EXPECT_EQ(15, task_runner->NextPendingTaskDelay().InMilliseconds());
 222 }
 223
 224 TEST(DelayBasedTimeSourceTest, HandlesSignificantTimebaseChangesImmediately) {
 225   scoped_refptr<base::TestSimpleTaskRunner> task_runner =
 226       new base::TestSimpleTaskRunner;
 227   FakeTimeSourceClient client;
 228   scoped_refptr<FakeDelayBasedTimeSource> timer =
 229       FakeDelayBasedTimeSource::Create(Interval(), task_runner.get());
 230   timer->SetClient(&client);
 231   timer->SetActive(true);
 232   // Run the first tick.
 233   task_runner->RunPendingTasks();
 234
 235   EXPECT_EQ(16, task_runner->NextPendingTaskDelay().InMilliseconds());
 236
 237   // Tick, then shift timebase by +7ms.
 238   timer->SetNow(timer->Now() + Interval());
 239   task_runner->RunPendingTasks();
 240
 241   EXPECT_EQ(16, task_runner->NextPendingTaskDelay().InMilliseconds());
 242
 243   client.Reset();
 244   task_runner->ClearPendingTasks();
 245   task_runner->RunPendingTasks();
 246   base::TimeDelta jitter = base::TimeDelta::FromMilliseconds(7) +
 247                            base::TimeDelta::FromMicroseconds(1);
 248   timer->SetTimebaseAndInterval(timer->Now() + jitter, Interval());
 249
 250   EXPECT_FALSE(client.TickCalled());  // Make sure pending tasks were canceled.
 251   EXPECT_EQ(16 + 7, task_runner->NextPendingTaskDelay().InMilliseconds());
 252
 253   // Tick, then shift timebase by -7ms.
 254   timer->SetNow(timer->Now() + Interval() + jitter);
 255   task_runner->RunPendingTasks();
 256
 257   EXPECT_EQ(16, task_runner->NextPendingTaskDelay().InMilliseconds());
 258
 259   client.Reset();
 260   task_runner->ClearPendingTasks();
 261   task_runner->RunPendingTasks();
 262   timer->SetTimebaseAndInterval(base::TimeTicks() + Interval(), Interval());
 263
 264   EXPECT_FALSE(client.TickCalled());  // Make sure pending tasks were canceled.
 265   EXPECT_EQ(16 - 7, task_runner->NextPendingTaskDelay().InMilliseconds());
 266 }
 267
 268 TEST(DelayBasedTimeSourceTest, HanldlesSignificantIntervalChangesImmediately) {
 269   scoped_refptr<base::TestSimpleTaskRunner> task_runner =
 270       new base::TestSimpleTaskRunner;
 271   FakeTimeSourceClient client;
 272   scoped_refptr<FakeDelayBasedTimeSource> timer =
 273       FakeDelayBasedTimeSource::Create(Interval(), task_runner.get());
 274   timer->SetClient(&client);
 275   timer->SetActive(true);
 276   // Run the first tick.
 277   task_runner->RunPendingTasks();
 278
 279   EXPECT_EQ(16, task_runner->NextPendingTaskDelay().InMilliseconds());
 280
 281   // Tick, then double the interval.
 282   timer->SetNow(timer->Now() + Interval());
 283   task_runner->RunPendingTasks();
 284
 285   EXPECT_EQ(16, task_runner->NextPendingTaskDelay().InMilliseconds());
 286
 287   client.Reset();
 288   task_runner->ClearPendingTasks();
 289   task_runner->RunPendingTasks();
 290   timer->SetTimebaseAndInterval(base::TimeTicks() + Interval(), Interval() * 2);
 291
 292   EXPECT_FALSE(client.TickCalled());  // Make sure pending tasks were canceled.
 293   EXPECT_EQ(33, task_runner->NextPendingTaskDelay().InMilliseconds());
 294
 295   // Tick, then halve the interval.
 296   timer->SetNow(timer->Now() + Interval() * 2);
 297   task_runner->RunPendingTasks();
 298
 299   EXPECT_EQ(33, task_runner->NextPendingTaskDelay().InMilliseconds());
 300
 301   client.Reset();
 302   task_runner->ClearPendingTasks();
 303   task_runner->RunPendingTasks();
 304   timer->SetTimebaseAndInterval(base::TimeTicks() + Interval() * 3, Interval());
 305
 306   EXPECT_FALSE(client.TickCalled());  // Make sure pending tasks were canceled.
 307   EXPECT_EQ(16, task_runner->NextPendingTaskDelay().InMilliseconds());
 308 }
 309
 310 TEST(DelayBasedTimeSourceTest, JitteryRuntimeWithFutureTimebases) {
 311   scoped_refptr<base::TestSimpleTaskRunner> task_runner =
 312       new base::TestSimpleTaskRunner;
 313   FakeTimeSourceClient client;
 314   scoped_refptr<FakeDelayBasedTimeSource> timer =
 315       FakeDelayBasedTimeSource::Create(Interval(), task_runner.get());
 316   timer->SetClient(&client);
 317   timer->SetActive(true);
 318
 319   // Run the first tick.
 320   task_runner->RunPendingTasks();
 321   EXPECT_EQ(16, task_runner->NextPendingTaskDelay().InMilliseconds());
 322
 323   base::TimeTicks future_timebase = timer->Now() + Interval() * 10;
 324
 325   // 1ms jitter
 326   base::TimeDelta jitter1 = base::TimeDelta::FromMilliseconds(1);
 327
 328   // Tick with +1ms of jitter
 329   future_timebase += Interval();
 330   timer->SetTimebaseAndInterval(future_timebase, Interval());
 331   timer->SetNow(timer->Now() + Interval() + jitter1);
 332   task_runner->RunPendingTasks();
 333   EXPECT_EQ(15, task_runner->NextPendingTaskDelay().InMilliseconds());
 334
 335   // Tick with 0ms of jitter
 336   future_timebase += Interval();
 337   timer->SetTimebaseAndInterval(future_timebase, Interval());
 338   timer->SetNow(timer->Now() + Interval() - jitter1);
 339   task_runner->RunPendingTasks();
 340   EXPECT_EQ(16, task_runner->NextPendingTaskDelay().InMilliseconds());
 341
 342   // Tick with -1ms of jitter
 343   future_timebase += Interval();
 344   timer->SetTimebaseAndInterval(future_timebase, Interval());
 345   timer->SetNow(timer->Now() + Interval() - jitter1);
 346   task_runner->RunPendingTasks();
 347   EXPECT_EQ(17, task_runner->NextPendingTaskDelay().InMilliseconds());
 348
 349   // Tick with 0ms of jitter
 350   future_timebase += Interval();
 351   timer->SetTimebaseAndInterval(future_timebase, Interval());
 352   timer->SetNow(timer->Now() + Interval() + jitter1);
 353   task_runner->RunPendingTasks();
 354   EXPECT_EQ(16, task_runner->NextPendingTaskDelay().InMilliseconds());
 355
 356   // 8 ms jitter
 357   base::TimeDelta jitter8 = base::TimeDelta::FromMilliseconds(8);
 358
 359   // Tick with +8ms of jitter
 360   future_timebase += Interval();
 361   timer->SetTimebaseAndInterval(future_timebase, Interval());
 362   timer->SetNow(timer->Now() + Interval() + jitter8);
 363   task_runner->RunPendingTasks();
 364   EXPECT_EQ(8, task_runner->NextPendingTaskDelay().InMilliseconds());
 365
 366   // Tick with 0ms of jitter
 367   future_timebase += Interval();
 368   timer->SetTimebaseAndInterval(future_timebase, Interval());
 369   timer->SetNow(timer->Now() + Interval() - jitter8);
 370   task_runner->RunPendingTasks();
 371   EXPECT_EQ(16, task_runner->NextPendingTaskDelay().InMilliseconds());
 372
 373   // Tick with -8ms of jitter
 374   future_timebase += Interval();
 375   timer->SetTimebaseAndInterval(future_timebase, Interval());
 376   timer->SetNow(timer->Now() + Interval() - jitter8);
 377   task_runner->RunPendingTasks();
 378   EXPECT_EQ(24, task_runner->NextPendingTaskDelay().InMilliseconds());
 379
 380   // Tick with 0ms of jitter
 381   future_timebase += Interval();
 382   timer->SetTimebaseAndInterval(future_timebase, Interval());
 383   timer->SetNow(timer->Now() + Interval() + jitter8);
 384   task_runner->RunPendingTasks();
 385   EXPECT_EQ(16, task_runner->NextPendingTaskDelay().InMilliseconds());
 386
 387   // 15 ms jitter
 388   base::TimeDelta jitter15  = base::TimeDelta::FromMilliseconds(15);
 389
 390   // Tick with +15ms jitter
 391   future_timebase += Interval();
 392   timer->SetTimebaseAndInterval(future_timebase, Interval());
 393   timer->SetNow(timer->Now() + Interval() + jitter15);
 394   task_runner->RunPendingTasks();
 395   EXPECT_EQ(1, task_runner->NextPendingTaskDelay().InMilliseconds());
 396
 397   // Tick with 0ms of jitter
 398   future_timebase += Interval();
 399   timer->SetTimebaseAndInterval(future_timebase, Interval());
 400   timer->SetNow(timer->Now() + Interval() - jitter15);
 401   task_runner->RunPendingTasks();
 402   EXPECT_EQ(16, task_runner->NextPendingTaskDelay().InMilliseconds());
 403
 404   // Tick with -15ms of jitter
 405   future_timebase += Interval();
 406   timer->SetTimebaseAndInterval(future_timebase, Interval());
 407   timer->SetNow(timer->Now() + Interval() - jitter15);
 408   task_runner->RunPendingTasks();
 409   EXPECT_EQ(31, task_runner->NextPendingTaskDelay().InMilliseconds());
 410
 411   // Tick with 0ms of jitter
 412   future_timebase += Interval();
 413   timer->SetTimebaseAndInterval(future_timebase, Interval());
 414   timer->SetNow(timer->Now() + Interval() + jitter15);
 415   task_runner->RunPendingTasks();
 416   EXPECT_EQ(16, task_runner->NextPendingTaskDelay().InMilliseconds());
 417 }
 418
 419 TEST(DelayBasedTimeSourceTest, AchievesTargetRateWithNoNoise) {
 420   int num_iterations = 10;
 421
 422   scoped_refptr<base::TestSimpleTaskRunner> task_runner =
 423       new base::TestSimpleTaskRunner;
 424   FakeTimeSourceClient client;
 425   scoped_refptr<FakeDelayBasedTimeSource> timer =
 426       FakeDelayBasedTimeSource::Create(Interval(), task_runner.get());
 427   timer->SetClient(&client);
 428   timer->SetActive(true);
 429
 430   double total_frame_time = 0.0;
 431   for (int i = 0; i < num_iterations; ++i) {
 432     int64 delay_ms = task_runner->NextPendingTaskDelay().InMilliseconds();
 433
 434     // accumulate the "delay"
 435     total_frame_time += delay_ms / 1000.0;
 436
 437     // Run the callback exactly when asked
 438     timer->SetNow(timer->Now() + base::TimeDelta::FromMilliseconds(delay_ms));
 439     task_runner->RunPendingTasks();
 440   }
 441   double average_interval =
 442       total_frame_time / static_cast<double>(num_iterations);
 443   EXPECT_NEAR(1.0 / 60.0, average_interval, 0.1);
 444 }
 445
 446 TEST(DelayBasedTimeSourceTest, TestDeactivateWhilePending) {
 447   scoped_refptr<base::TestSimpleTaskRunner> task_runner =
 448       new base::TestSimpleTaskRunner;
 449   FakeTimeSourceClient client;
 450   scoped_refptr<FakeDelayBasedTimeSource> timer =
 451       FakeDelayBasedTimeSource::Create(Interval(), task_runner.get());
 452   timer->SetClient(&client);
 453   timer->SetActive(true);  // Should post a task.
 454   timer->SetActive(false);
 455   timer = NULL;
 456   // Should run the posted task without crashing.
 457   EXPECT_TRUE(task_runner->HasPendingTask());
 458   task_runner->RunPendingTasks();
 459 }
 460
 461 TEST(DelayBasedTimeSourceTest, TestDeactivateAndReactivateBeforeNextTickTime) {
 462   scoped_refptr<base::TestSimpleTaskRunner> task_runner =
 463       new base::TestSimpleTaskRunner;
 464   FakeTimeSourceClient client;
 465   scoped_refptr<FakeDelayBasedTimeSource> timer =
 466       FakeDelayBasedTimeSource::Create(Interval(), task_runner.get());
 467   timer->SetClient(&client);
 468
 469   // Should run the activate task, and pick up a new timebase.
 470   timer->SetActive(true);
 471   task_runner->RunPendingTasks();
 472
 473   // Stop the timer
 474   timer->SetActive(false);
 475
 476   // Task will be pending anyway, run it
 477   task_runner->RunPendingTasks();
 478
 479   // Start the timer again, but before the next tick time the timer previously
 480   // planned on using. That same tick time should still be targeted.
 481   timer->SetNow(timer->Now() + base::TimeDelta::FromMilliseconds(4));
 482   timer->SetActive(true);
 483   EXPECT_EQ(12, task_runner->NextPendingTaskDelay().InMilliseconds());
 484 }
 485
 486 TEST(DelayBasedTimeSourceTest, TestDeactivateAndReactivateAfterNextTickTime) {
 487   scoped_refptr<base::TestSimpleTaskRunner> task_runner =
 488       new base::TestSimpleTaskRunner;
 489   FakeTimeSourceClient client;
 490   scoped_refptr<FakeDelayBasedTimeSource> timer =
 491       FakeDelayBasedTimeSource::Create(Interval(), task_runner.get());
 492   timer->SetClient(&client);
 493
 494   // Should run the activate task, and pick up a new timebase.
 495   timer->SetActive(true);
 496   task_runner->RunPendingTasks();
 497
 498   // Stop the timer.
 499   timer->SetActive(false);
 500
 501   // Task will be pending anyway, run it.
 502   task_runner->RunPendingTasks();
 503
 504   // Start the timer again, but before the next tick time the timer previously
 505   // planned on using. That same tick time should still be targeted.
 506   timer->SetNow(timer->Now() + base::TimeDelta::FromMilliseconds(20));
 507   timer->SetActive(true);
 508   EXPECT_EQ(13, task_runner->NextPendingTaskDelay().InMilliseconds());
 509 }
 510
 511 TEST(DelayBasedTimeSourceTest, TestOverflow) {
 512   // int(big_now / interval) < 0, so this causes a crash if the number of
 513   // intervals elapsed is attempted to be stored in an int.
 514   base::TimeDelta interval = base::TimeDelta::FromInternalValue(4000);
 515   base::TimeTicks big_now = base::TimeTicks::FromInternalValue(8635916564000);
 516
 517   scoped_refptr<base::TestSimpleTaskRunner> task_runner =
 518       new base::TestSimpleTaskRunner;
 519   FakeTimeSourceClient client;
 520   scoped_refptr<FakeDelayBasedTimeSource> timer =
 521       FakeDelayBasedTimeSource::Create(interval, task_runner.get());
 522   timer->SetClient(&client);
 523   timer->SetNow(big_now);
 524   timer->SetActive(true);
 525   EXPECT_EQ(0, task_runner->NextPendingTaskDelay().InMilliseconds());
 526 }
 527
 528 TEST(DelayBasedTimeSourceTest, TestReturnValueWhenTimerIsDeActivated) {
 529   scoped_refptr<base::TestSimpleTaskRunner> task_runner =
 530       new base::TestSimpleTaskRunner;
 531   FakeTimeSourceClient client;
 532   scoped_refptr<FakeDelayBasedTimeSource> timer =
 533       FakeDelayBasedTimeSource::Create(Interval(), task_runner.get());
 534   timer->SetClient(&client);
 535
 536   timer->SetActive(true);
 537   task_runner->RunPendingTasks();
 538
 539   // SetActive should return empty TimeTicks when the timer is deactivated.
 540   base::TimeTicks missed_tick_time = timer->SetActive(false);
 541   EXPECT_TRUE(missed_tick_time.is_null());
 542 }
 543
 544 }  // namespace
 545 }  // namespace cc